One of them is in each region with Team Rocket heading over the region. Their main attraction is to catch a Legendary Pokémon. Usally in the region they are in. There is about six including the secret Squad. So maybe five that Ash has beat. They all want a powerful one. They will not stop until they get it.

Groups

Team Rocket Pokémon: Mew & Mewtwo Failed

Team Galactic Pokémon: Giratina Obtained

Team Magma Pokémon: Groudon

Team Aqua Pokémon: Kyogre

Team Dim Sun Pokémon: Darkrai

Team Plasma Pokémon: Zekrom and Reshiram Failed