You want to know what the problem with starters is? They're too strong. In other monster collection games, starting monsters are designed to be weak for a reason; you're supposed to replace them with better monsters as you progress through the game. Pokemon has this balance problem where players don't feel pressed to replace them after a certain point, resulting in general poor game experiences all around.
So how can this be fixed? Simple, just reduce their BSTs by 60 each. 10 points per stat. That way people will be encouraged to box their starter once they get to the point where they can catch a pseudo legend or something. This will have the positive side effect of having players appreciate other pokemon instead of hyperfixating on starters.