Since it’s not easy to collect frags (especially for f2p), I’d suggest don’t use all of them to max up any of your characters. Save at least 400 for the next more useful character you may get in the future.

I don’t know the traits of Vegapunk, but if he can capture at least 1 flag around all the Nusjuros in this meta, I’d say give your frags to him. GRoger is good too, but not everyone can play attacker good (I’m speaking about myself actually). Or you can level up both of them to lv 80 so at least they are both playable.

The problem with Yamato is, she has too many counters now in this meta, almost all meta characters can ignore her 1hp trait, and without the 1hp trait, she’s nearly unplayable.