Cure: Poison would be Uber situational even more than Stop: abilities and the only reason that was added was because SoA was running rampant, and that is not happening with poison. The other idea is better, but there is already an ability called strike back.
As for my idea, There could be a series of "turn after" abilities, like power +2 , opp. attack -7 min 5 , damage -2 min 1 , or even SoA . This would add a whole new game mechanic, although the SoA and SoB ones could be overpowered because of the ability to make say Rolph and all stop making him almost unstoppable.
I have an idea of : pioneer: ability where you can only have this ability at the VERY 1st round doesn't matter if you go 1st or 2nd, it will activate and can't be negated, but only usable at 1st turn. and another one which is the opposite to it, not sure of a word for it but you can get it if you use it at last turn. thost ability won't be game turning but it will be vert strong for the standards now.