Bibarel
I've tried out the Bibarel before, I was pretty excited when I found out about his trait. Not quite so much when I learned that you can't go beyond 4x boost, but he is still pretty damn formidable with a Swords Dance and some speed passed to him. I used a Scizor to pass an Agility and Swords Dance, but Ninjask would probably work even better.
I've run some of the calculations, and he can OHKO almost any non-uber after a Swords Dance. There are some that can take one hit, like Metagross, Skarmory, and possibly Dusknoir, but some of those can be beaten with only a power-boosting item. Choice Band pretty much ensures that you will OHKO the first thing you hit.
Return and Waterfall are no-brainers (the 30% flinch from Waterfall would result in even a dead Skarm) and the only Poke that resists both is Empoleon. Dig might be useful for scaring off Metagross, unless he's already picked EQ of course. Superpower beats some Pokemon he might otherwise have trouble with (like Empoleon) at the cost of likely ruining your streak with the attack drop. Amnesia will triple his special D, so that is worth considering also.