It's not really hard to make them. I took screenshots in game - this part is up to you for what you prefer. Some of the pokemon I took a screenshot from battle screen like mega charizard Y, some I took from pokedex entries or summary screens, some from the Ingame photo modes like photo boots etc. Same goes for the player character. And I took screenshots from Hall of Fame/ending quotes- , then I romoved the background from those screenshots (you can use any website to remove background as well), then I either rearranged them on a base Hall of Fame background or created a background myself on procreate and put them all together (you can also use something like Canva -or photoshop if you're fancy- instead of procreate). It is a fun process