A combo I saw SemiiJ do in the corner, and I believe this is the highest damage Meterless (that I'm aware of anyways?)
F343, B22xxTelekickxxAirsai, D1, 4xxRoll, run under D2, 21xxRoll, Roll - 45%
Although this is meterless, it's near impossible to connect F343 if you're playing anyone with two...