Vegetto is a very powerful fighter, and Super Vegetto is stronger than the SSJ4 forms of Goku or Vegeta. The only downfall is the fact that he is a potara fusion, meaning that if you fail the initial attempt, you are left with a watered down Goku/Vegeta for the rest of the fight. If you are successful, you are given the strongest permanent fighter in the game.
Goku(Pre-fusion)
Vegeta(Pre-fusion)
Vegetto
Forms
Base--130% attack--6 ki baseline
Super Vegetto--145% attack--MAX ki baseline(7 ki bars required)