[SSJKarma]

first: vegeta said it himself when he was against zarbon. everytime a saiyen is defeated by someone, he gets back with TWICE STRONGER than he was when he gets beaten ! now i think that means i am right about it !

second: put that in real life, if wqe train toi be able to lift 1 ton then after a whole lots of training, we will be able to do so ! now why is this not possible in the DBZ universe ?
example:
KRILLIN was powered up by GURU in the namek saga !
guru said that he had awakened ALL his hidden power !
now, if i follow your reasoning, he wouldn't be able to use more than that power cause he was already at the max of his own power ! but then, he was a lot stronger than that at the end of DBZ.

third: you cannot put the saiyens as there power is, you said it yourself unlimited, that means they will always win whatever you say against it ! but the mutants have their power and do not get stronger like the saiyens so yes they can be included in the fight as they aren't INVINCIBLE ! ok !

now i know what you're gonna say...
GOKU, VEGETA had already die so they aren't invinsible !
true about that... but still, vegeta got beaten like hell by zarbon and he came back and it was the other way around ! and vegeta never trained ! and zarbon was way higher in power than vegeta ! goku was beaten to death then he healed in that chamber and he got to way higher powerlevel than he was before. he had no training ! by definition i think it is a little overpowered !