Kind of iffy, you see Master Roshi bust a moon(although he used his strongest attack still an impressive feat) and they only get stronger after that. I have to finish reading 666 Satan to fully understand how strong Jio is.
He has the potential to beat most if not all villains in the series. He's not beating any of the Z warriors though (maybe Majin Vegeta). Jio doesn't win fights base off his stats. He wins from speed+hax. Any of the villains in the series will die just from Zero, think of it kinda like the Devilmite beam. The more evil you are, the stronger zero becomes and it goes past your durability by attacking the soul. That being said, he can possibly take out Any incarnation of Buu, but he'd still lose to someone in Namek saga who isn't evil, for example, Goku.