You wont get coin for the dot damage, only what you cause by hits, for example Mei barrier poison damage before her actions works, but when the cat suffer poison and ignite at turn end wont. Even if you kill the cat like that, not much more coins.

Alinho, I think its better to do the extreme cat, u can get more money from it, just be carefull you wont die.
Immobile debuff works very well or accu point, because the cat mystery hits a bit hard.

I use Cho, Mei, Ao and water main or
Mifune, Darui, Cho and Midnight

Fire Main teams with Iruka works too.

Yea u are right, I checked, its really stacks dot damage for the coins.