@0takuDragonSlayer
The thing is, Koga's not just shitting all over his returning-stars trainers with secret talents, he just passes their basic challenges surprisingly well. That makes all the difference right there. No one likes legacy characters being steamrolled by the new shithead kid, and it's not what's happening here. It's the balance between potential and still being an outsider, where plenty of manga would just have the protagonist wipe the floor with their mentors. With Koga, the Asura characters are still the centerfold, absolutely at the top of their game and training a rookie, nodding at how he's a pretty damn good student, because it's satisfying to them to see someone learn their craft without talking shit. That's why José was so angry at dickhead Fang. He clearly sees Koga as a talented lil' bro he wants to support with all his heart.
So yeah, pretty sure the theme here is "Legacy characters are as badass as ever, and are undoubtedly the in the main action, but Koga slowly inherits their skills so he can save the day by the end". Just imagine.
Suikechi teaching him how to improve his perception, and Chiba Takayuki, how to use it to switch fighting styles on the fly.
Yoshinari teaching him to switch to different kinds of gravity and balance.
Muteba teaching him to wear a crisp suit, and also use his body as a weapon, maybe.
Gaolang teaching him how to control the flow of battle
AG teaching him to adapt and learn in the heat of battle
Hatsumi, how to chill the fuck out and dodge like a pro until the opportunity for the killing strike
Many of the fighters' special skills are physically inclined, like Wakatsuki, Kure Rian, Bando Yohei, Saw Paing, The Beard and others, so they can't realistically "teach" what can't be taught, so Koga can't end up a litteral superhuman, but there's a legendary final battle chock full of twists against an incredibly overpowered and incredibly unlikeable enemy waiting to happen.