Another RoF/Super Fix.
Redo RoF with Yamcha, and Chaiotzu included... You increase tha bad guy's power and have all the humans die when Togama and them step in.
You then have Tenshinhan, Chaiotzu, Yamcha, Krillin, and Muten Roshi all go to FINISH their King Kai training.
Muten Roshi keeps out of the training until the guys start working on the Kaioken with Muten Roshi criticizing how the Kaioken is inferior to his buff form due to the risk of self harm.
However their argument turns into an accidental collaboration that brings about a new and stable Kaioken for the humans to learn and master, and later bring out in the ToP.
















