It sounds passable, but ironically it has same plot as the worst Rocky movie, Rocky V.
In both Rocky V (1989) and Creed (2015) Rocky has hung up his gloves and retired from the sport, and wants to stay out of the spotlight, but is persuaded to come back when he takes an aggressive young boxer under his wings (Tommy "the machine" Gunn in V, Apollo Creed's illigimate son in Creed), and agrees to serve as his trainer.
Audiences still wanted to see Rocky punch someone in V, so the movie includes a street fight between Rocky and Tommy. I heard there's a similar scene in Creed: some punk kids attack Rocky, and he beats the snot out of them.
