>>12617764If you have a friend who wants to get back into Pokemon, it's not always best to start with a new generation, metaphorically speaking. It is best to always start with a remake, and that's because if they like the remake, you can move them onto another generation that you'd think they'd be interested in.
OP, have him start with HeartGold first, and then introduce him to Platinum, then you introduce him to a Gen 5 game, I would go with White 2 though if he doesn't care about story