I would like to know some of you fans' favorite retro Pokémon version(s). Mine are Platinum and Emerald because of the Battle Frontiers. It can't be 3ds.
I'd have to go with Pokémon Platinum. It's the Pokémon game I've replayed the most, and I always have a good time with it. I often have a hard time branching outside my favorites in the region though, as most of my teams have Luxray and Staraptor. Pokémon Emerald and, if I can count it, Gale of Darkness are the other two I think of very fondly.
Diamond is my definitive favorite. I played it and pearl the most of any game in the series. Sinnoh has it's issues, but I still consider it my Pokémon home.
Gen 5 had my favorite games in the series for a long time, but going back to them I don’t enjoy them the say way I used to despite the nostalgia. Now I think my favorite older Pokémon game is Emerald. The expanded story is a blast, the postgame was incredible for the time, and the games are so snappy and responsive to play. If they had better EV training, IV breeding, and a physical/special split they’d be tied with Sun and Moon for my favorite Pokémon games.
Probably Platinum or HeartGold/SoulSilver. If I'm allowed to, I will say Pokémon Mystery Dungeon: Explorers of Sky. I actually like PMD more than the main series.