Fighters who peaked in their teens

I just saw 19 years old Marvin Sonsona beating Jose "Carita" Lopez for the WBO Super Flyweight title in 2009. The announcers claimed that He became the youngest Filipino boxing champion in history, but I think that's incorrect and He's actually second to Morris East, mentioned earlier in this thread by @LWW .
Sonsona then failed to make weight and was held to a draw in his first title defence against Alejandro Hernandez, got stopped while fighting for vacant belt at 122 (So moving up 2 divisions) and while He fought on and off until 2022 - He never regained his old glory.

 

He was hugely rated as a young phenom at the time in Panamanian boxing. They expected him to be a pound for pound star and ended up partially ruining him by pulling their association clout and rushing him into that famous fight with Hong. I think he was 17 at the time?

 

Yeah. That's one of the legendary fights that you learn about early on when you get into watching old boxing because it's one of the all-time comebacks. At some point I found out just how old Carrasquilla was and I became more impressed by the fact that it was just a kid who was giving it to the ex-champion in there.

Putting him in a fifteen-rounder against Pedroza might have been even more ill-advised. Dunno if his team had given up on him by then, or if they didn't know just how good Pedroza was yet, or if there was some pressure on them to make the first all-Panama world title fight. He's done well for himself since boxing. He spent fifteen years as the mayor of one of Panama's most populous districts.

 

Would Kid Chocolate be a good example?

Not sure he peaked at 19 but he was a smash even then.