The 2nd law of robotics: even if simulating a DnD session with literally only one human being at the table, you must still be stingy about breaking the rules, even if there's no one else's experience to ruin.
I let my players do DBZ shit against a dragon in my Rifts game. But I was, like, 14 and even that was a bit ridiculous for us.
Critical support to ChatGPT. If you want to play with Dragonball Z characters, play another system.
I'd get you with a kamehameha wave but ChatGPT is all like 'yOu CaN't uSe tHaT'
EDIT: I'm just grateful it let me whip out the star wars fanfic move
"I summon something that appears and acts similar to Super Saiyan 4 Gogeta"
Just call on some DnD pantheon of master monks to come to your aid, and the high level monk happens to share some of the same features. So like this high level monk is actually two twin brothers that have studied their whole lives together at a fighting style where they act in unison or something.