PokemonRomHacks also has plenty of guides and tutorials to help you get started downloading and running emulators.
If you are looking for more information on how to find, download, or even make your own ROM hacks, check out the resources found in PokeCommunity. Fan games that use copyrighted material, such as Pokémon, cannot be sold or used to make any profit.
Note: Pokémon fan games are not officially approved by Nintendo and therefore within their legal rights to take down. One of the best sci-fi games ever made is coming to Nintendo Switch next month