Notices:
1: Values are based on statistical averages. Rounds assumed to survive are 5 full turn cycles. I will be running additional values of 7 rounds, 10 rounds, 12 rounds and 15 rounds in a later post to see if that causes any number fluctuations.

2: This does not take any gear, shard availability, marks or any forms of cultivation. This is based on values provided by the Illustrations of them at level 200.

3: Despite silence being arguably significantly stronger than 50% damage mitigation. 50% Was used for simplicities sake as that would greatly augment these results even further in cells favor due to having a more prevelent silencing mechanism. So please note I do understand assuming only 50% is very low and doesnt take into account for heal blocking or detonation blocking, or additional bleed stack blocking. Its just a flat value to go off.

=BASE VALUES=
-------------------
Cell
ATK: 70877
HP: 1491751
DEF: 17401
SPD: 410

Buu
ATK: 70877
HP: 1413364
DEF: 12548
SPD: 419
__________________
Cell has higher base values other than speed.
ATK: 0
HP: 78387
DEF: 4853 = 4% Damage mitigation
SPD: -9
__________________

50% Silence for 1 turn, 3 Targets
15% Teleport, Once a turn (full damage mitigation)
50% Heal once per battle
12% Dodge, Restore 35% Energy increasing Silence consistancy

Taunt for 1 turn forcing default attack
15% Teleport, Once a turn (full damage mitigation)
30% Block, 20% Chance to Chocolate for 1 turn. Applies Once each 2 turns.
30% HP Revive once per battle.

=Active=
Cell: 1/2= 50% | 1/4= 25% | 1/8= 12.5%| Or alternatively, 87.5% chance for 50% Damage mitigation with a 12.5% chance for 150% damage mitigation. (50% over 3 characters). Something to note is due to randomness, This can prevent Detonation and also push heals/shields back a turn as well.
Kid Buu: Garunteed 50% Damage mitigation always against highest attack which in current meta is Vegeta Majin, Or later is Vegito.
====== Result ======
Cell, having a significantly high damage mitigation potential while also having the ability to delay healing or bleed detonations.


=Passive 1=
Cell: 15% Teleport.
Buu: 15% Teleport.
====== Result ======
Tie, Easy one here.


=Passive 2=
Cell: 50% Heal once per battle
Buu: 30% Revive once per battle. (drops all buffs/debuffs)
====== Result ======
Tie, while the effective regain is significantly less, being able to drop all debuffs or bleed stacks makes up for that 20% life descrepincy. This is being generous as we're assuming the tanks will survive a 5 full turn cycle. Meaning that the debuffs would have to account for the full 20% of the damage taken which obviously is incorrect given the attacks that cause the bleed stack but there are so many variables here, calculating it would be far to much work to figure out all the variations.


=Passive 3=
Cell: 12% Dodge, Restore 35% Energy limit to 5 times a round. Given the 5 turn cycle, He will get 2 activations, which equates to a bonus 2.45% damage mitigation. Totaling his damage mitigation from this skill to 12+2.45%=14.45% Damage mitigation from final passive.


Kid Buu: Base block mitigation is 30% damage. With 30% chance for it to occur. If we continue using the standard of 5 turns, and assume every turn is a singular attack which is being very generous. thats 5x5=25 Total attacks. 30% of 25 is 7.5 For the sake of our previous generousity. We'll round to 7.
7 Total blocks in his life span. with a 20% chance to apply the chocolate, Means he has a 140% chance of it applying atleast once within his life and given the 2 turn delay. Its exceptionally unlikely for him to get a 2nd chocolate as he doesnt statistically reach 100% until last attack turn 3. meaning cycle 4 and 5 couldnt occur. So with 1 activation likely during his life span, we can run 1 of 25 attacks to be mitigated, equating to 4% damage mitigation. 30% Chance of block for 30% Mitigation equates to 30*30%=9% (or 30*.3=9). Totaling 4%+9%=13% damage mitigation from his final passive.

====== Result ======
Cell retains the lead with a 14.45 damage mitigation vs Buu's 13% mitigation.



========================================= FINAL MITIGATION RESULTS =========================================

Cells Total Damage Mitigation: 23.2% from Skills
Buus Total Damage Mitigation: 16.4% From Skills.

Cells Total Base Mitigation: 16% from DEF stat
Buus Total Base Mitigation: 12% from DEF stat

Combined Total Mitigations for Cell: 39.2%
Combined Total Mitigations for Buu: 28.4%

Effective Health of Cell: 2,076,517 EHP
Effective Health of K.Buu: 1,814,759 EHP
Total Effective Health Difference: 261,758 HP.