If it's a dirt-old stock trope, then that doesn't really change much; instead of the trope being taken from OOOs its just being taken from the land that time forgot.
Well, yeah. If you have a problem with shows being cliched, Wizard is clearly not something you'll enjoy. The series has pretty obviously been designed, consciously, as a massive pile of genre cliches.
Personally, though, I think there's a big difference in terms of "using an old stock type that's been around forever" and "copying something specifically from another show." The former will not necessarily be interesting but is fair game. The latter tends to stick out a lot and be extremely obvious, even if the copied element otherwise works well enough.
Shunpei wasn't even that bad. It's not like Gai where he spinning and jumping all over the place in every scene. He can be a lot worse.
Man, I'd trade Shunpei for Gai in a heartbeat. Junya Ikeda in a Rider show, even playing a douchey supporting character, would be a dream come true.