Hey if you need suggestions for Vegeta's B attacks maybe he could use Genocide breaker (The move he uses to kill Jeice) as his side B. BTW who is Vegeta going to be over?
In PSA, there is a tab called "Run Initial Velocity". Simply make this a higher number. The lowest I believe is about 1.1 for Jigglypuff. The highest is 3.5 for Sonic (just to give you an idea of the sort of bounds).