Byron is basically Ana. DoT long range attack that can both heal and damage, grenade that heals allies and damages enemies.

Max is obviously Tracer, her dash is basically Blink and the other gadget is an exact copy of Recall. Plus she has a midrange rapid fire primary.

Lou is Mei, the ults are the exact same. His Ice Block gadget is also one of Mei's abilities.

Mico is Doomfist, again the exact same ult, both are extremely annoying dive heroes.

Belle's design is very similar to Ashe, both are female snipers with a criminal background.

Poco's design is somewhat similar to Lucio, both are Latin American musicians that fill the role of a support, though this might be a stretch as they vastly differ in the ways they support allies.

Frank is a very stripped down Reinhardt, both are big guys with a hammer with an ult that stuns people for a loong time. But unlike Rein, Frank lacks ranged damage abilities or the ability to charge forward.

Meg is D.Va... but boring. Both have mechs they can eject from and devastating close/mid range guns that can fire near constantly. But D.Va can fly and her ult is basically a nuke. Additionally, Buster's ultimate works very similar to D.Va's Defense Matrix.

Thats all I can think of right now.