Support Pokémon is unlocked 75 together with Mirror Challenge, which is a game mode that you can get materials to level up your Support.
Pokemon Tier List 1000 Fire Books - Pokeland Legends
How to get Legendary Pokémon on Pokeland Legends. Catch Legendaries in Pokeland Legends
Best Costumes of Pokeland Legends, Costume Tier List
The passive of Overlord or Resonance Lugia plays a big part in this team, allowing Pokémon that use non-attacking skills to move again (Lugia and Ho-Oh's buff)
Disclaimer: This is a basic recommended build. Please keep in mind that some builds might need to be changed in order to adapt your pokémon to the current meta, or to simply adapting yourself to the enemies that you play against.