Did you find that socially isolating at all? On one hand, and probably more a thought from my adult brain than something I would have agreed with back then, one doesn't want friendships that are predicated on such things. On the other hand, it sure looked like they were having a lot of fun playing Pokémon, whereas I didn't know the first thing about it. It would have been an easy thing to use as common ground.
Watching your friend's Tamagotchi while they're away sounds almost humiliating though.