Depends on the team of course, but here are some standards that I typically fall back on. In no particular order:
Bulky pivot: Landorus-T, Rotom-W, SpDef M-Scizor
Speed control / revenge killer: CS Excadrill, Talonflame
Electric check: Yache Landorus-T, CS Kyurem-B
Bird check: CS Excadrill...