So simply put I only know of these two games :

Pokémon Revolution
PokeMMO

Which one of these is more popular? Are there other games similar to these that I haven’t heard of? Let me know thanks.

I think I’m going to start Pokémon Revolution soon. I think people call it PRO?

Lemme know if you play thanks

Pokemon planet pretty fun, grindy but extensive

pokemmo is extremely active

I still play PokeMMO and its active.
They do seasonal events and stuff also

Games i've played:

PokeMMO : Very nostalgic and moddable if you like fancy sprites etc, also extremely active in terms of competitive PVP
PokeOne: not too many players but very beautiful game, i liked shinyhunting here. also has daily/weekly boss encounters n stuff
Pokemon Planet Online: Extremely grindy. Played for a year then got bored of it, end game that make hunting easier are stupidly expensive due to the fact they only drop very rarely from world bosses (have to get top damage ranks to even have a chance)
PRO (revolution online): same as PokeOne pretty much, fancy with good end game content.

I probably will go back to PokeMMO soon. Only thing i dislike there is the fact that hunting shinies is terrible. last time i played shiny odds were 1/20000 iirc.

hf!

Tried them all for a decent amount (around 25-50 hours) and sticked to Pokémon revolution online!

Best lategame, pvp, events and most activity ~ alrdy around 250 hours+