Pokemon spinoffs before: Soulful, a one time purchase, games of mixed quality; some comparing to mainline games and others are duds, but all are still playable to this day if you're interested.

Pokemon spinoffs now: Free to start, almost all available on mobile, barely have any "gameplay", gachashit, if you want to play them 5-10 years after their release you're out of luck (Sorry duelbros)