I found a Brazilian community server getting ready to open and it is focused on AllTheMons with a big arena duel system.
They made their own serverside mod called CobblemonArena so you can join without installing anything and just fight.
You can do direct challenges or jump into matchmaking with commands. When a battle starts the arena closes up in a circle so nobody can mess with it.
Duels run with a 10 minute timer and 6 Pokemon with free switching. You win by having more Pokemon still alive and ties go to whoever has more total HP.
There is no automatic healing after a duel so your team leaves the same way it entered and every match feels serious. People can also watch as spectators and the results post to Discord with a ranking bot.
They are still finishing development and the server is not open yet but they say they are close.
AllTheMons Arena Duels With Ranked Queue
GG.MINEWIND.NET New Server IPTubalith Competitive PvP Network Just Launched
Tubalith is a PvP first network where the point is to fight and keep progressing not to get babysat in survival.
The SMP has real stakes with PvP on and base raiding plus looting allowed. People make alliances then start wars and sometimes backstab each other.
There are custom Legendary weapons and armor that change fights but they use ability cooldowns so it stays more skill focused and not pay to win. KOTHs happen multiple times per day and new Legendaries drop weekly.
Duels are fast arena fights with competitive kits and a ranked ELO system. Battle Royale is also here where you drop in loot fast and only one player or team wins.
Coins are mostly for cosmetics and effects so it is about style and showing off not buying wins.GG.MINEWIND.NET New Server IP