If you are looking to play these classic Java files on modern hardware, you can use specialized emulators:
A direct, official port of Pokémon Ruby to J2ME does not exist. Nintendo guarded its IP fiercely and was not in the business of licensing its crown jewels to competitor phone manufacturers. So, what were these files that millions were playing?
: Simplified Java RPGs that use assets from the Generation 2 or 3 games. Chinese "Meiwu" RPGs