The Pokemon Company is not nearly as hawkish with their IP as people say. They shut down a handful of fan games a couple years ago but they've just kinda given up on that it seems. There's so many hugely popular ROM hacks that streamers play on twitch, clearly using emulators, and TPC does nothing about it. Wolfey Glicke, a VGC player who has done many official collaborations with Pokemon, has played them on stream and made videos about it on Youtube.

It seems like Pokemon has decided it's not worth the hassle or maybe they see benefits in letting them exist (many of the biggest Pokemon creators basically only play ROM hacks), either way they haven't shut down Pokemon-related fan projects in ages.