Either works, but enemies is probably easier to work out. Friendly could be interesting but we'd probably have to make it so that their somewhat balanced in terms of power, else it's not much of a rivalry; with enemies we can just have them dislike each other for personal reasons, but if we want them to compete with each other then we might have to finagle some stuff; say that Akeno's Quirk counters hers or say that one is strong where the other is weak, physical strength versus Quirk strength for example, while keeping things somewhat fair and also explaining the difference in their student rankings.

Hmm, I don't know, Akeno's a complicated person at times. We should probably discuss this through PMs or on the discord when that's up.