What are the good teamfight junglers?

Honestly, all JG are pretty weak at the moment as a whole. With the JG changes it can be difficult to positively as opposed to negatively impact a lane.

Right now Khazix is stong, but not a teamfighter. I generally did well with Amumu, but again, with the jungle nerfs I don't see how he can contribute much of anything. He was struggling before the nerfs but at least had gank potential, right now like many junglers, he just doesn't have that fear factor.

All said, I don't think there are any teamfight oriented junglers that can actually do well at the moment. Amumu is the closest IMO, but I seem to do better with him than many others. (though it's all relative to rank eh?)

Edit: Just going through, Karthus clears really fast and could be considered more teamfight oriented. Gragas is okayish with his ult, Sejuani has a good presence. I can't see anyone else really that I'd brand as a "teamfight" champ in the jungle. So that's 4 champs I guess, none particularly strong today.

There are a few others that I guess might be okay, but basically, there are 0 that are really on par with champs like Kha'zix as far as impact on the game. Sejuani is probably the best of the ones I listed anyway.

I just like playing Hecarim, using predator boots, youmuu's ghostblaede, ghost summoner, E dash, and Q + Ultimate, to delete whoever on the enemy team is already damaged, and my ultimate carries me through and to the other side of the rest of the enemy team, AoE damaging them, and then Nimbus Cloak kicks in, allowing me to escape through the other side of the thick team fight. The enemy team turns to chase me, but Nimbus Cloak is just too good. My teammates are free to disengage or continue chasing them who try to chase me. I'm in your red already, half a screen away from all of you. In other scenarios where I can press the advantage, I don't run away, Helicopter Q spamming them along with my team for the ace.

TLDR Use Hecarim for hit and runs. Dashing in from afar, you convert 4v5's into 4v4's, or, if you stay post-dash, it's a 5v4.