Aceraspire said:
There's already too much outliers in DBS,it's getting ridicillous.If writter wants him useful and more powerful then he will be.It's normal for DBZ & DBS to get ridicilous power up
The problem is though that unlike the Saiyans who achieve new transformations or use techniques(Kaioken for Goku) to get these power ups. Roshi is just an "ordinary" human who can't transform and most likely does not have a technique that would warrent such a massive boost. So unless Roshi or someone else says he's been training it's unlikely to be legitimate.
That being said though, I wouldn't be surprised if there aren't at least a few participants from other universes that are vastly weaker than Goku, Vegeta, Hit, etc. that Roshi would be able to fight on even ground.