>>43309455I always dislike using Pokemon from other gens, I know it's autism but some real sinnohan fire types would be nice, I think. It would be similar to what they did to kanto with mostly dark variants.
For the puzzles, I imagine you could do something about finding information in different places (the library for example) which would help you track down Uxie. For Mesprit it could be something about friendship levels, maybe? And Azelf a big maze, almost tedious but fun nonetheless, that would use all of your willpower to finally get to him. But those are just examples of how you could make them more relevant (a secondary typing could be good for them too)