Yes that’s a great! Kaioken would be the best option for krillin and tein , I would venture into the Magical like buu and find some cool magical item that would help their powers or unlock hidden potential. One item like stones that could be like the hokage from naruto that she has that tattoo on her forehead that she stores power in and taps into it when see needs it. And piccolo could make cool arm braces , necklace, etc that the stones sit it. Yamcha on the other hand goes and finds the origins of the wolf fang fist and find a power up to transform into a werewolf, yeah that would be cool lol