Tyson is one of Ash's friends who lives in Mauville City. He won the Hoenn Tournament as first place by defeating Ash.
Season 8: Advanced Battle
He first appeared in Like a Meowth to a Flame, where he saved Ash, May, Max and Brock from a flock of Murkrow who attacked them. Later, he was seen carrying the Moltres flame for the Hoenn Grand Festival and battled Team Rocket for it.
Metagross was the second Pokemon on Tyson's team. It appeared to recover the Moltres Flame from Team Rocket. It later appeared to battle Ash's Pokemon in the Ever Grande Conference. Against Swellow, it used its Psychic attack to freeze Swellow and lower its defenses while defeating it with a Hyper Beam. Against Grovyle, it took a couple hits from Bullet Seed and knocked Grovyle out with Hyper Beam before Leaf Blade was used. It battled and fell to Ash's Pikachu.
Sceptile is Tyson's third Pokemon seen at the Ever Grande Conference. In a double battle with Johnny's Aggron, it managed to use Detect to dodge Metal Claw and then defeated it with a SolarBeam. During the battle with Ash, Sceptile used SolarBeam against Glalie's Ice Beam, but caused an explosion that knocks them both out.
Tyson's Donphan was the fourth Pokemon revealed to be on his team. Along with Sceptile, Donphan was seen on the scoreboard knocked out with Johnny's Blastoise in the premilinaries of the Hoenn League Ever Grande Conference.It reappeared in Tyson's battle with Ash's Swellow. Donphan used Sandstorm and then landed Rollout on Swellow multiple times until the Swallow Pokemon hurled it back and slammed Donphan on its back, knocked out.
Hariyama was the last of Tyson's team to be used in the Ever Grande Conference. Hariyama was used in the battle with Ash. It fought and defeated both Ash's Corphish and Torkoal, but fell to his Swellow.