Isaac is one of the legendary RPG fighters who knows how to fight in many different styles. Give him a blade or his fists and Isaac will churn out a win either way. Alas, he won’t be able to defeat Vegeta. Just having access to light type abilities isn’t enough to beat a true Super Saiyan of legend. The gap in their raw power is too significant and the same can be said about their speed. Vegeta wins.