Fighting game ai isn't something I'm super experienced with, but here is how I would start.
Make a hidden sprite, pin it in front of Vegeta. When you (his enemy) aren't within his range, have him start to move toward your direction, then once in range, do something like this.
Set move(variable) to "floor(random(1,4))"
if move = 1:
move forward 0.3 sec, then punch
if move = 2:
move forward 0.1 sec, then punch
if move = 3:
move forward random(0.01,0.6), then punch
if move = 4:
move backward 0.2
move forward 0.8 then punch
this would be kinda predictable, but would be a start.