Roshi is 100, Yamcha is 60 (or something)
Yamcha attacks, Roshi dodges with ease, someone weaker could replicate the feat but it'd be hard for them
Yamcha uses WFF, Roshi wakes up a bit to dodge this one since it's a bit faster
WFF is over, Roshi is chillin again and Yamcha backs the fuck off
Fight with Krillin starts and Roshi's chillin so he's caught a bit off guard at Krillin's speed, but regains composure quickly and retaliates, knocks Krillin on his ass. Krillin gets up and then the two really go at it.
Something like that, anyway. I don't fight.
ahill, those examples are different. Roshi is at level x and is using less than x. Goku and Piccolo are at x and are using x, but can power up beyond x if they so desire. This is where Dragon Ball diverges from real life because in real life you don't power up. You would have to think of Goku and Piccolo using full effort as if that were their full strength. It's not comparable to Roshi here.