There is A Pokemon MMO Called PokeMMO

Pokemon multiplayer

Why aren’t you playing yet? It’s (hopefully) everything you wish Pokémon was!

Download for Windows, Mac, Linux, Android
pokemmo.eu/downloads

Uses ROMs to dodge Nintendo’s hammer
https://vimm.net/vault/?p=list&search=pokemon&submitButton=Search

Why play?
-Competent AI adds challenge to your gameplay

-Levels are capped per badge to ensure battles are balanced, EXP isn’t lost

-Follower Pokémon

-You can challenge other players to duels

-You can spectate other players’ battles

-It’s an MMO, shiny values are not damaged by external cheat devices, making some extremely rare and valuable.

-IVs and EVs add actual value to a Pokemon

-EVs/IVs are visible in a Pokemon’s summary window

-Smogon Tier system, OU, UU, NU, LC, Dubs, Trips, Rot., 4 player Contests

-PvP automated matchmaking for quick and easy duels

-Ranked PvP ladder

-Breeding is important to creating a competitive team

-Competitive Pokemon are worth more money.

-Official PvP tourneys/catching comps with shiny prizes

-Holiday events with exclusive prizes

-Tons of user ran events

-Vanilla regions to relive childhood

-Kanto, Hoenn, Unova, and soon Sinnoh

-Freely switch between the three regions after your first 4th badge

-Battle Frontier can be played co-op

-4 player Contests (Gen 3 Contests)

-In-game Market and Global Trade System

-Pokédex contains useful information, such as learnsets and egg groups

-Fair degree of Player Customization, including attire based on other franchises

-‘Ocarinas’ that act as a reusable HM that doesn’t need a Pokemon; Collect em all and cast aside your HM Slaves

-Gen 7 Learnsets/Stats/Abilities as long as they exist in Gen 5

-All Pokémon can learn their event moves from any gen if they have one

-Gen 6+ weather changes

-BW seasons, also changing every month in Kanto and Hoenn, not just Unova