I usually get 7-15 kills before team fights but when TFs begin I find myself completely usless. Is there a way I can help in TFs? What are some other junglers that have a presence in a TF?

Udyr is an amazing jungler in general, and Shaco generally falls off as he enters later levels. I hope that helps.

Mundo has great teamfight presence. Shaco falls off hard once teamfights begin because he doesn't do a lot of AoE damage and isn't very tanky.

Shaco is OUTSTANDING at backdooring and side pushing if you can get your team to stall the Tf and buy you time to take a ton of permanent building HP while the other team is distracted.