Catch or obtain a Cobblemon that can be ridden
Make sure the Pokémon is large enough and has riding enabled
Put the Pokémon in your party
Use the ride keybind or interact with the Pokémon while holding the required item, if your server or modpack uses one
Mount the Pokémon when the ride prompt appears
Use movement controls to steer while riding
Dismount using the default dismount key
Check server settings or modpack controls if riding does not work
Verify the Pokémon species supports riding in your version of Cobblemon