In each generation, there is typically at least one group of Legendary Pokémon that form a trio. Each Trio is seemingly subject to another Legendary Pokémon.
- Regice, Regirock and Registeel – The Legendary Golems (Regi), ruled by Regigigas.
- Groudon, Kyogre and Rayquaza – The Weather Trio. The master of this trio is in fact, Rayquaza itself.
- Uxie, Azelf and Mesprit – The Lake Trio, ruled by Arceus.
- Dialga, Palkia and Giratina – The Creation Dragons, ruled by Arceus.
- Reshiram, Zekrom and Kyurem: The Tao Dragons, ruled by an unknown master.
- Cobalion, Terrakion, and Virizion: Three Pokémon based on the titular characters of the novel The Three Musketeers. This trio does not have a master, however, it is rumoured that Cobalion may be one.
- Keldeo: The fourth member of the Muskteer Trio, thus making them a quartet.
- Tornadus, Thundurus, and Landorus: Based on three Japanese gods known as kami, with Tornadus based on Fujin, the god of wind, Thundurus on Raijin, the god of thunder, and Landorus on Inari, the fertility god. Landorus is the master of this trio.