What would you want a mainline pokemon game set outside of Earth to be like?

There's been numerous references in the franchise about some pokemon being from space and also many references about humans trying to achieve space travel.

The possibilities are endless. Going through several planets as you do with cities or focus on a single region of an alien planet/moon?
Alien cities or human space colonies?
Spam clefairies and elgiem everywhere or focus on brand new alienmons?

Lets throw in some ideas or wishlists just for fun!