that wouldnt make sense. if ssj are stronger in the series why should others have boost? With the SSJ stamina burning timer idea that grega suggested, it would get much more balanced and wont break the Dragon Ball Z character's characteristics. So an SSJ 2 would be stronger than an android or picollo form 2, but would not last forever because would have to recharge stamina making him temporaraly weaker, making balance
:EDIT:
oh and non sayans characters also have others advantages, like heal (majin buu) , low PL burn wille swoop (picollo or krilin), like not get detected on radar (androids), and if the buddy system works perfectly with no bugs, in fact it can be very damagable if you can dominate the art. For example when an enemy is going to attack your buddy you can take the buddy off and attack the enemy from the side much easier way, and then call buddy back to make double quantity of KI blasts wille he's getting him self together.