I've been considering a sort of space-themed worm Pokemon based on a "wormhole" but I'm not sure what type(s) to make it (maybe Psychic?) or what sort of moves it might get besides teleport or ally switch (or maybe "Hyperspace Hole", but that's the sig move of Hoopa). Any ideas?
Psychic is a pretty common type for space-based things, from what I’ve seen, so that could easily work. Dark and ghost are the other two semi-obvious ideas, or maybe water if you want to go the palkia route (I believe common consensus is that it’s a water-type due to the fluidity of space). You could probably slide another type on there as a dual-type, but that may mean basing it on a little more than just wormholes: maybe rock if you want to throw in some planets (that it might have burrowed through?), or fire for stars. Maybe steel, and base it partially on space ships that travel through wormholes?
Those all sound like good move ideas to me, even hyperspace hole if you don’t mind hoopa sharing its sig (just stay away from hyperspace fury, which seems less thematically appropriate and also literally doesn’t work if anything other than hoopa unbound uses it). Those are the only examples I can think of that closely resemble or reference wormholes, but other, less-wormholey-but-still-appropriate ideas include cosmic power, gravity and perhaps future sight. It might also be an interesting candidate for one or more of trick room/magic room/wonder room, or any of the moves that swap stats or abilities around (skill swap, guard swap, etc.).
You can also come up with your own sig move or sig moves, of course! The sky’s the limit with that.