Hydreigon is the fourth Pokémon in Camron's team, and was also his "secret weapon". It is the first Pokémon chosen by Cameron against his top 8 league battle with Ash in Strong Strategy Steals the Show!. The battle continued in Cameron's Secret Weapon!, where it was shown to be a very powerful Pokémon. It first battled Ash's Boldore. Both Pokémon fought hard but Hydreigon easily dodged all of Boldore's attacks, while landing hits with Tri Attack and Dragon Rush, and finally knocked him out with Dragon Pulse, which easily overpowered Boldore's Flash Cannon.
Despite the notable size difference, Ash's Oshawott proved to be a reasonable opponent for the Brutal Pokémon, right away scoring a hit with Aqua Jet. Hydreigon came back and avoided Oshawott's Razor Shell before striking back with Dragon Pulse. Despite taking damage from the hit, Oshawott went on with another Razor Shell, which hit one of Hydreigon's heads, and then scores a direct hit on the Brutal Pokemon with Hydro Pump. Hydreigon then fires a Tri Attack, which Oshawott is unable to block, taking more damage. Oshawott fights back with Tackle, but his following Razor Shell was countered by Hydreigon's Double Hit, which was then followed by a Dragon Rush, finally defeating the Sea Otter Pokémon.
Ash's Pignite, is what finally faints the beast, though it was no easy battle. Hydreigon scored several powerful blows, but Pignite uses Fire Pledge to force Hydriegon into flight, and then scores a direct hit with a super effective Brick Break, which knocks Hydreigon out.
In A Unova League Evolution, the score board showed that it had lost to Virgil.