I'm gonna hafta say FB Snorlax or FB Machamp. Zappy can get the **** beat out of it by bliss's 3hko icebeam, yet drillpeck is only a 3hko itself providing blissey doesnt use softboiled. Tyranitar's Rock slide is also a 3hko providing blissey doesnt softboiled or counter. Snorlax can very easily 2hko blissey with Doubleedge, and fireblast will 2hko skarm. Machamp can very easily OHKO blissey with CC, and fireblast will 2hko skarm. Then again, the whole concept of switching makes a huge difference in this scenario.