Does Repel work on Entei on Poemon Firered?

Answer 1

the way that repel works is that if something is lower level than your lead pokemon, you will not get in a fight with it.

so if you're level 71, you won't run into a wild entei because entei is level 40

Answer 2

yes it does, it is level 40 when you meet it, so have a level 39 pokemon as the first one, that way you can repel everything else.