Notes
I will explain the cards but if you wish for more in-depth information, go to https://www.carddass.com/dbh/sdbh_ugm/cardlist/ with a translate add on or utility, can copy the card text and paste it to google translate if you're a ningen. And Dimpsu, if you are reading this, pls WM2, I need the localized goodies so I don't have to cry on not letting my deck building autism flow, and you know that you can make it a masterpiece, H1 -> UGM5. Also for possible card choices, this won't be 100% complete, hundreds to thousands of combos, just the initial ones that came to my mind that I thought were noteworthy.
CellMax Deck tl;dr
The idea of the decks are to synergize with CellMax, reducing enemy DMG reduction and STA to great effect by exploiting the fact he doesn't care if his HE is destroyed, BM11-058 Goku (Xeno) will solidify R1's state of HE while Trunks (Xeno) will stay in the back until he needs to be an attacker to prevent HE destruction, allowing an easy 3x alongside super attacks. Will try to acclimate to the hellworld meta that SDBH is in, though note that it is fierce when you try to ignore things like UGM2 Piccolo (SH) and Gohan (SH) or other such staple options for the sake of utilizing the deep card pool (i.e. Being a hipster). Or by using the fact he's the best way to hurt one's self (don't read too far into that) with 5k fixed damage if you don't have HE while he's a supporter, meaning it's possible for him to get you low enough to proc 'comeback' effects reliably.
Core Cards
UGM4-066 CellMax (SH):
The main impetus for the deck, he's a giant that when a supporter, he destroys half your HE rounded up to gain PWR, reduce enemy STA, and increase the damage the enemy takes, exact math is 1.1x if 1 HE's destroyed, 1.2 for 2, 1.3 for 3, 1.5x for 4, and then 3x for 5. IMPORTANT NOTE: If you were to play in the Arcade, have Trunks (Xeno) be registered first so that he can proc ahead of CellMax, they both activate after choosing attackers/supporters and this is the way to make it where Trunks can protect your HE before CellMax destroys them. If needed, he can also be 5k fixed damage but it applies to both players.
UM11-SEC Trunks (Xeno):
When an attacker, prevent destruction on your HE, also gain 1 HE. He has a freeze attack, cool, barely matters, he has a unit, flavor text. He is the simplest switch for HE preservation from CellMax, Gotenks requires you to have less than the enemy at the start of a round, Gohan (Xeno) is round 3 only, the BMP-15 Trunks (Xeno) requires you to have used a unit.
Really Good Synergy Cards
UGM4-047 Vegeta:
At the PLBP, he gives you 1 HE while destroying an enemy's HE, if your own HE was destroyed before hand, this goes to +/-3 HE, and when he attacks, he gains PWR based on how little HE the enemy has, at 0 he gains 100k PWR, and has a counter rush to delay your death if on the back foot alongside Trunks (Xeno)'s freeze attack.
UM12-066 Vegeta (BR):
Vegeta (BR) gives ally attackers 5k PWR and 3 HE at the PLBP if your HE's been destroyed, this goes up to 10k PWR and 5 HE if you have Goku (BR), and in terms of making sure your team will have HE to follow through on subsequent turns, really good. A thing to note is that when you attack with Trunks (Xeno), this card will do nothing, and that Vegito (Xeno) from UGM3 will prevent you from generating HE with this card, hence why he isn't a core card.
UM11-063 Goku (BR):
He restores ally STA, and gains PWR LV, this makes him really good here since he can be fast enough to get PWR LV without needing to be from an ability, but it isn't fixed PWR LV so Aeos flags you as gay, though against (SH) centered decks this card's speed is appreciated.
UM6-050 Goku (BR):
Gives allies 5k PWR and if you attack with 5 or less, and gives you clearance against Hellfire God Meteor, disabling DMG Multiplication/Increases is fine because we're making the enemy take more damage, not making us deal more damage.
BMP-15 Trunks (Xeno):
This card gives you 5k PWR to all allies at the start of the round as well as KI DMG resistance, but the main thing here is that he can protect your HE if you've used a unit. There is a possibly way to go into unit turbo or just to have it so you can use this after a PWR LV Limiter or similar unit but for the former, UGM3-068 Vegito (Xeno) will rape you for such a foolish notion, there's a reason that not even Bardock unit turbo lives anymore, and for the latter, it is an option but I prefer the very selective nature of Trunks (Xeno), where I can just plug him into an attacker and not worry about having too few HE to use a unit to go for broke or for having it be disabled in one way or another, and is much kinder to card slots since I don't need to make sure I can fit a unit on the team alongside other choices.
ABS-014 Super Buu (Buuhan)
When your HE's been destroyed, he lowers enemy PWR, problem is that it's 1000x, you need 5 destroyed just to break parity with any number of PWR generators, doesn't really fit here and more with BM11-ASEC2 Goku, if the math was something like 3000x, definitely strong consideration, but mentioned here as he's the lone card that will give her defense as a synergy with HE destruction, all others give you some variance of offensive pressure to my knowledge.
ABS-015 Gogeta (GT)
Gives your team PWR/GRD based on your HE, with which increases if you have an ally with low PWR/GRD, while it may be counter-intuitive, with cards like Vegeta (BR), or just on the turn you go for the kill with Trunks (Xeno), he can boost the team's PWR/GRD by 10k real nicely, or 20k if someone's been hit by Aeos' keysword.
UGM4-064 Gohan (SH)
When he attacks an enemy, depending on the damage dealt, he'll reduce the enemy team's STA and increase your HE, the less damage the better (0-1k, 1k-5k, 5k-10k for the brackets), and his CAA is a gangan impact in which he and 4 partners gains 3k PWR per HE you have. He's really good in general and would help solidify this deck. Trivia, he doubles his PWR LV at the PLBP, why? Idk, because they needed to fill text I guess. With his PWR LV Limiter unit, you could add in the UGM2-065 Piccolo (SH) and UGM4-062 Goku (SH) for a strong (SH) core with unit to use, leading you to being able to slap on BMP Trunks (Xeno) instead of UM11-SEC Trunks (Xeno).
Fears
UGM1-SEC Aeos:
-100k PWR/GRD Keysword, 'Time Prison' which is when if they have an ally with less than 100 pwr, disable resurrection and miracle perfects on your end, 1 HE unit to reset everything to 0, and if you have a Super Ability, she can destroy her own HE to disable it. Finally her ability allows her to disable fixed PWR LV on you as well as halving the PWR/GRD of three heavy hitters. Note that for Super Ability, this includes Climax and summons. Last I knew she was/is Tier 0 Meta Mommy and she's a Tier 0 Meta Mommy for a reason. Also Aeos appearing means you have
UGM1-061 Bardock in Black
So his summon, R2 onward, permanently disables ability-based HE generation as well as slight PWR generation and KI DMG resistance, and with the terror down below, you can kiss HE generation via abilities goodbye. Helps solidify the pain train of the Aeos core alongside UGM1-062 Namekian in Black.
UGM3-068 Vegito (Xeno):
Very common, hits hard, gets 4k PWR LV, and disables HE generation from abilities while they have 75%+ HP, this can be a huge damper and also put some really nice cards from core, into niche since he pretty much disables such shenanigans, poor one out for HUM4-022 Strongest Human.
HGD9-04 Trunks (Future):
I've seen this card come up and limiting your PWR LV to 5k puts a damper on things, now add Vegito (Xeno) on top of it and the specter of death shall soon come for you.
My Deck; Sane version
So for a rundown of how it's ran, it's kind of player judgement, and preserving some STA while generating it so that when the time comes that you feel comfortable, then go ahead and get 10 HE for lethal. The big things to note for using your Zamasu, just remember that hellfire god meteor is delayed so if you think R3 is going to be a lethal round, even if the defensive stance wouldn't be too good, you'd need to have him as an attacker R2 to get the Hellfire God Meteor in time, and it's okay to have him a supporter R1 if you don't think he'll defensive stance much even if it'd get in the way of HE generation for CellMax. And if worst comes to worst, such as the enemy having UM8-047 Fin or similar cards, having the HA means you can eat 5k dmg from CellMax, and it does hit your opponent too so that's less health to eat through. ABS-03 Vegito can be a bit of a party pooper since he'll seal super attacks on your highest hitters but with the pwr generation, and that he only hits on three allies, so you should be fine. A big thing is to try to play around enemy Android HA, if you can tell they have less than solid STA generation than you can try to play around that to prevent them from being fast too, especially before going ahead towards lethal rounds. For capsules, sadly I'm not too informed on them beyond a few big ones but use to judgement, be wary of when the 7k PWR LV Limiter drops from the enemy or if they SH Unit you a round, could be rough to defend on R4 if you used Zamasu earlier in the game. And as always, good luck on the CIs and don't be too tilted on miracle perfects, it's a rhythm game based on your CI speed, press enter/the button before you feel its perfect so that you can make up for the time spent pressing it/clicking the mouse or else you'll overshoot.
BM11-058 Goku (Xeno)
Welcome to the laboratory of jank! He helps secure R1 HE to go for bigger shredding on R2 with his ability while also possibly slowing the enemy down as well. As for the fusion, it's huge PWR, huge HE, and some speed, and the pool for Vegeta (Xeno) pool isn't as bad as one might think, there were about three options. Also you get to be awesome having SS4LB Gogeta (Xeno) instead of some gay SSB nonsense, until you see his Super attack and remember the importance of speed lines. Still cool to give this card the time of day though.
PBBS11-05 Vegeta (Xeno)
So this and BM11-060 were really close at first, BM11-060 helps you get an easy win in initiative on R2 with halving their PWR LV, but this comes with some caveats. Aeos doesn't care because of her to fit him I'd need something like PUMS9-18 Kefla or similar, even if we got 10 HE for CellMax. Having a shield burst is also welcome against the rampaging Gotenks, GRD breaking Gokus, and other heavy hitters. This helps really give a good defensive foundation since this can handle with fixed damage, something Zamasu can't handle. Finally, what else was Vegeta (Xeno) going to do, the final option was PCS17-01 which had Battle Pride (team gains 2k PWR for each HE you have over the enemy, has synergy with the fusion as well as extra PWR), but that'd require a good deal of testing, something I lack until Dimpsu blesses us with WM2. And the absolute final option is BM12-HCP5 where he has a God-bird link, we want that for the alpha strike which is after he's fused, not before so this deck doesn't really utilize, one that has a card that really cares about winning CIs, or even perfect CIs, could appreciate this though.
BMPS-06 Merged Zamasu
It's more than just Zamasu fanboy autism here! Defensive Stance + Hellfire God Meteor, what more could you ask for on a defensive card? Stupidly good card, staple promo ever since he was unveiled for two good, yet simple reasons.
EL Android HA
Very original, I know, but hey, this is card is dumb for a reason, strong STA generation, strong PWR disruption, strong CAAs in double attack and dragon fist, huge ass HP since it's a HA, you can't go wrong with marrying this cyborg even if I'm not that kind of person.
OR 
OR 
BM7-060 Golden Frieza (Xeno) OR BM9-066 Shroom OR UGM3-030 Goku (GT)
So there's many options for this slot, what I wanted was some form of speed and/or STA regeneration, less hipster options include BM12-SEC, fixed damage is really nice as is not being an EL but so is the 10k PWR he gives when he restores the STA of allies in critical condition, problem is he requires that to be in a pinch, so not as totally reliable but in a world of BMPJ-48 Bardock, UM8 Goddess Putine, and UGM4-064 Gohan (SH), it'd be appreciated. Other options included UGM1-SEC2, who not only offers some STA regeneration but also powerful defense that lets you survive a strong EL co-op attack, also gives you a Vegeta that increase STA DMG dealt in case you ever wanted him alongside some special attack sealing if the enemy has too much HE but with Goku (Xeno), may not be needed. Alongside the other half a dozen cards, from old to new, I narrowed it down to three cards. UGM3-030 Goku (GT), BM7-060 Golden Frieza (Xeno), and BM9-066 Shroom. Let's start with Goku (GT), he has a very good shenron wish that doubles special move damage alongside free HE, and his STA regeneration also comes with resetting the PWR of allies with less than 100 PWR to 3k, not as good as initial values but still really welcome as protection against the Supreme Kai of Doom and her Vegito husbando. Golden Frieza is here because I don't think negative PWR exists so if he procs, even to an ally with 1 PWR, he'll do more to them, also if you do get below half health, he brings 2 bars of STA to everyone and 10k PWR, very good, but above 50% and he can't even restore 1 bar of STA, only doing a half. Finally why Shroom, and also why not Shroom, he restores STA to ally attackers based on your HE alongside disabling their DMG multiplying effects for the round, this is where research is a bitch because no up to date simulator, from what I could tell, he doesn't work against Hellfire God Meteor, the biggest thing he'd be a counter against nowadays, so while he'd be neat, his dark shenron's not enough to carry him, it only lowers enemy PWR LV by 25%, so that 21k cap is now sub 16k, and this is ignoring any boosts that come along or the fact Aeos laughs at this gesture entirely, and while the stun on command could come into use to make full on offensive rounds that much heavier and act as an extra defensive utility, it kind of requires you to lead ahead and have STA interference that sticks against UGM2-065 Piccolo (SH) and friends, if I had better tools to test, this could be more solidified but as of now, it's leaning more towards Goku (GT) with Golden Frieza (Xeno) and Shroom as more tech options rather than something I'm comfortable main-decking on the face of things, with more experimentation, perhaps Shroom could have a home.
UM11-SEC Trunks (Xeno)
UGM4-066 CellMax
They're the thesis of the deck, 3x DMG reduction is no joke when put behind some heavy hitters, while it doesn't work with every CAA/TAA, there are many that it does work with, and dragon fist is one of them. One final thing to note is that Trunks (Xeno) must be registered before CellMax so that the order of abilities will go Trunks (Xeno) -> CellMax, if the other way, you'll end up with 6 HE instead of 10, same applies to Goku (Xeno), make sure he is registered before CellMax for this same reason.
My Deck; Berserker Variant
The goal of this variant is to be a defensive deck that shreds with CellMax's 5k fixed to both parties, and then obliterate on the crack back when you hit 50% or less hp. One thing to note is that this is probably the most volatile of deck construction due to its attempt to be both fragile but not too fragile, that there is much one could edit this depending on preference and fears. Currently it doesn't use an HA giving it an HP of 18300 to 20200 depending on cards chosen, note that 20k or below is a critical checkpoint since that means that regardless of enemy dmg dealt, we'll be at 50% HP R3 because of CellMax, but this could also threaten us with death by CAAs/TAAs. When you're at 8.5k and are staring down an EL Android HA, it can be a bit frightening even if the passive playstyle of this variant means she won't have that much PWR to work with.
OR 
OR 
UGM3-065 Piccolo (SH); HP 2800 OR SH2-SEC Cell (Xeno); HP 2600, OR BM1-SEC3 Bardock; HP 2000
So the first two are simple, preference, you want them as lone attackers R1 because you want as little HE as possible until you break the 50% threshold (the 1k PWR round means you'll get 1 HE by r3 no matter what unless no attackers are present which this deck doesn't do). Piccolo has 200 more HP but it doesn't break thresholds here, he does slightly more damage but Cell (Xeno)'s utility is more preferred, could help get extra damage stunning someone with him and then landing someone's boosted CAA/TAA against that stunned guy but that's an edge case considering CAA/TAA targeting is random. And for BM1-SEC3, what Bardock does is when attacked, reduce damage dealt by 90%, and afterwards double his PWR and gain 2k fixed damage to his special move as well as having climax, that when fully done and he becomes SS4, he gains 10k PWR LV and PWR, and as this is fixed, it is something that Aeos cant wish away, now for the problems. First, Bardock is deleted from existence if the enemy has DMG reduction pierce or strong CAAs/TAAs, of which BM7-SEC Masked Black is both, and still sees some play even if UGM2-SEC2 Goku/Jiren scared him away, and secondly, he can be stunned, meaning you need to be on your game with the CIs or you blow up. Bardock does come with the upside of opening up the 2nd slot though. even if you want it to just be filled with a card that prevents stun like BMPS-08 Goku (Xeno), PCS12-11 Gotenks, PBBS12-01 Aeos, or PCS17-03 SSR Masked Black, HP ranges from 3k - 3.6k, which accounting for Bardock's low HP, not too much a difference as to break checkpoints. If I had more knowledge of meta, I could be more comfortable with BM1-SEC3 but otherwise I'd go with UGM3-065 Piccolo (SH).
OR 
UGM4-SEC Vegito; HP 2900 OR BM5-ASEC Vegito; HP 2200
Welcome to slot two of your defense option, there's many, many options one could go over, I picked Vegito Blue because the ASEC is one of the safer options but the other option also does things. Before going into the cards here, there's dozens of cards here, the main thing is you want an attacker you can sit out alone as to not generate HE and not explode, right now I did Laggs because I felt the CI could help but there's advantages to having a 3 card defensive core and either cutting Laggs or replacing Cooler (Xeno) with Laggs. You could have Aeos, Warrior in Black and ABS-03 Vegito in these slots and do very comfortable even without the unit. So for the cards, UGM4 not only reduces enemy DMG dealt but also increases his damage and PWR LV, all great things, all things Aeos can disable with a unit. So ASEC Vegito has it where when he's an attacker, he'll only take 2k DMG from co-op attacks, this means we have two rounds where we can't die at all outside of CAAs/TAAs. Though to note with BM5-ASEC, you MUST win the CI against Aeos' keysword, there's a chance it'll target someone else if the player doesn't know what this Vegito does but if they do and target it, loosing that CI and having him be disabled pretty much means death since there's no defense otherwise outside of praying you win every CI and have CellMax as an attacker.
UM8-059 Laggs; HP 3500
So the idea is to help secure the enemy's death by disrupting their STA and CI, making it easier for you to secure wins when attacking and sort of control the damage when defending, you don't have to press the red button after all and for decks like this, it is a common tactic to do this when against health thresholds and hope the right player looses. Alongside Golden Cooler you fear very little, BM9-SEC3 Frieza does exist after all and we have no out other than him never appearing, Aeos does exist after all. This is also a very flexible slot, could strengthen the defensive core to help against huge PWR, could reassure against CAAs/TAAs (such as by being a HA).
BM7-064 Golden Cooler (Xeno); HP 2900
At the start of a round he'll reduce enemy STA by half a bar and their GRD by 2k, if you have 50% or less hp this raises to an impressive 2 bars and -5k enemy GRD, really useful to make the enemy be at full mast throughout the game and also prevent their GRD from getting too big.
OR 
UM4-032 Gohanks (Xeno) OR UM2-SEC2 Golden Cooler; HP 3300 or 3700
So when your HP is at 50% or below, you restore STA of all allies and permanently double their PWR LV, this is like giving one of your guys an 8x PWR LV multiplier, and if the enemy somehow didn't implode into dust, imagine the thick, lip-smacking juiciness of getting this to proc twice, 81k PWR LV, fucking yes, could still lose to BM11-SEC2 & BM10-070 Bardock but that combo's thankfully less prevalent, but there's one problem, Aeos, timing wise she would be able to use her unit after Gohanks (Xeno) proc'd and her unit hits against PWR LV multiplication, not Fixed PWR LV boosting, hence why Golden Cooler's here, 99% of the time I'd rather Gohanks (Xeno) but Aeos unit makes him a possible liability. Another boon that could be welcome is that Golden Cooler has a lock-on that reduces the enemy's GRD to 1 and increases their CI speed, so he could help in other niche situations like with BM7-SEC Goku or retargeting shenanigans with Robel, CellMax doesn't always win against BM7-SEC because he proc's after strategy's decided, before any form of STA generation happens in the PLBP, though I think that's a bit rare nowadays.
BM11-069 Kid Fuu; HP 2600
This card does two things depending on your HP, if you have 50% or more, you disable the enemy's miracle perfect chance as well as -2 to their HE, which could be useful to prevent a R1 unit or keep them off foot, but if you have less than 50%, you instead get energy guard for the round which means you can go for the alpha strike with 10 HE.
UGM4-066 CellMax; HP 1800
Main crux of the deck, 5k fixed damage to both teams and then wrack them with that 3x dmg reduction when you go for broke. Will note here that you could replace Laggs here with a card that cares about having 10 HE since of the Energy Guard from Kid Fuu, and not using abilities to generate that HE, it's really reliable to do so.
NOTE:
BS Female/Male Saiyan BS HA, SS4LB If applicable
So this would replace Golden Cooler (Xeno) were it not for the fact I don't know how this card exactly this card works, need an anon to let me know how her BS ability works, raw footage is best but does she shred enemy DMG reduction or increase her damage, and is it a permanent boost? Also info with SS4LB on the saiyans will confirm this card's placement or not, as well as testing obviously, since you'll have 30k HP, you may want to be able to take more damage and as such the defensive core here would have to be changed as well.