Captain Aiden is a firefighter who also trains Squirtle, Wartorttle and Blastoise to aid him in putting out blazes and rescuing for anyone trapped in the fire.
Team Blastoise are used for putting out big fires, Team Squirtle is used for seach and rescue as they can fit into small gaps and Team Wartortle are used to put out most fires.
When Captain Aiden is not on call he keeps all the Pokémon in shape by having them run around a track or shoot at targets to improve their accuracy.