[Ability]Send Me Out With a Bang

Name: Send Me Out With A Bang
Effect: When a pokemon faints, it detonates, causing 20% of max health damage to opponet.
Secondary Effect: None.
Description: After fainting, the pokemon naturally uses a numbed form of Explosion to further damage it's opponent.(NOTE: If the Pokémon with this ability is fainted, the Pokémon counts as being fainted and THEN the explosion happens. In other words, if it was the last of a one-on-one fight, and the Pokémon with this ability is fainted, the one who delived that attack will be declared the victor.)
Looks: Looks exactly like the move explosion.
Type: Offensive
Pokemon: Any pokemon that can learn Self-Destruct or Explosion.

Let's say, it's a one on one and your one last friend faints. The foe has a tiny bit of health left in him and this ability is used, your foe will faint. Repeat process in the next battles, and there you have your sure win.

I suggest you change stuff here.

Edited, nerfed it's power a bit and edited it so that in a one on one fight, if the pokemon with this ability is fainted, the pokemon who delivered that attack is declared the victor. In other words, the Pokémon faints, then delivers the attack.

I don't get it. This kind of ability doesn't work the way it is. Why? Because we don't have any systems involving stats, and you're bringing "20% of max health damage". In Pokemon, Health is a stat just as much as the others. We can't approve this anyway.

I don't know how much you know about Abilities, but there's a pre-existing one called Aftermath that essentially does what this ability tries to do, and has a reasonable trigger and damage. Only like, 8 Pokemon in total have this ability. Your ability goes above and beyond a pre-existing ability, that is essentially the same thing you've tried to create.

Aftermath (Serebii Ability Dex)

I'd say no to this, simply because a similar ability already exists.