(I have Scarlet, not Crimson, but...)

Which of your main's attacks interrupt? Use that. It's... really good.
Unless you have another earth type on your team that's worth it, I'd avoid "Enhancement of Earth Types". Jirobo has the same thing, though, and I'm pretty sure they stack - actually, yeah, they should.

Hinata combos with almost everybody and she interrupts too.
Kakashi combos well too but he dies really fast.
Chiyo is good when I've fought her. Her mystery made me lose in the arena once.
Lee/Gai's leech is really useful and sometimes with one of them you don't need an actual medic. I'd use one anyway, though.
Speaking of medics, I suggest Kabuto since he's great, but you don't have him... try Karin; I know she has a Sasuke/lightning main combo that's pretty lethal. Her I think you just have to get right.
Gaara is a really good tank but he doesn't combo at all.
Tobi's a good troller since people don't really know how to attack him but they want to wipe him out (it's taijutsu, not mystery).

Honestly I'd go Jirobo/Choji/Chiyo but I don't know how that'd work exactly.

Hope this helps!