Well, I do have a list of spinoffs I wouldn't mind having, but there are a few that I am CRAVING to have and play.
A game that is similar to Colosseum/XD is #1 on my list! I don't care if it's Genius Sonority or a different company that wants to make this, I just want to play something like this again! These games were played differently, which I liked. The plot was much better than almost all(if not, all) of the handheld games IMO, and the games had a slightly higher difficulty curve, which is much appreciated for someone like me. They haven't done this since the 3rd generation, and now that the Pokemon count has doubled, I'd like to see this happen someday. Hell, it could even take place somewhere else, not involving Orre, just bring this back!
Pokemon Snap 2 for the 3DS/Wii U is pretty much #2 on my list. I've always loved playing Snap on the N64, and the way it was presented. Although I don't care for games with backtracking, Snap did it right. I'm tightening up my nostalgia goggles here, hoping to see this game come back again looking beautiful on a modern console.
PMD and Ranger were fun back then, but I'm just not too crazy for these spin-offs anymore, so I could care less if they came back. Conquest was great, it brought something new to the table, which is always appreciated. However, I can wait quite a long time for this to be made again, if ever. It seems like a standalone kind of Pokemon game.