i don't like it, sorry (i'm not the final word on it, mind you)
i'd love to have cameron in but the whole game has you using 1 pokemon at a time and the follower thing fits the friendship increasing with steps taken with them in first party slot thingIf this is to happen at all, there should be designated spots where this is possible (as it happens with Cameron in HG/SS and his photos). While move learning could be difficult to implement (there's move tutors for that), the places could have different effects (train up EVs, gain happiness, chance to find items...). It might not work as he says, but it does work.