I can handle Tsunade in 2-3 rounds no problem, but the slug absolutely destroys my team before I can really do anything.

I'm at 8100 power as an earth main, and lvl 47.

Is there a trick I'm missing for the slug, or did I push as far as I can realistically go without beefing up some?

I'm f2p for the moment, so my lineup options are mostly restricted to the usual suspects (the only ninja I've pulled was Sai who I randomly got from survival trial)