Vincent picked Chikorita as his Starter Pokémon from Professor Elm.
Seeing Jimmy and Marina being attacked by Team Rocket, Vincent arrived with Meganium. It used Solar Beam to stop Team Rocket's Steelix's Rock Throw attack. Meganium then repeated its attack, which Steelix endured and went to retaliate. It then used Solar Beam to attack the crystal's shell, to shatter it and free Raikou from Team Rocket. As Raikou and Marina were taken by Team Rocket, Jimmy, Eusine and Vincent went to rescue them. Upon Marina's rescue, the Trainers sent their Pokémon out, including Vincent's Meganium. Meganium used Light Screen to protect itself and others from Team Rocket's Pokémon, but suffered Attila's Muk's Sludge Bomb. Meganium and others stroke Team Rocket's crystal to weaken it, allowing Raikou to recover its energy and defeat Team Rocket, causing them to retreat.
Meganium first appeared when it, Vincent's Azumarill and Ash's Bulbasaur and Squirtle saw an apple on a tree. Bulbasaur and Meganium used their Vine Whip to fetch the apple, they both pulled to try to get it, but the apple snapped in half so everyone was happy until Azumarill threw the apple at Squirtle thinking it was funny. The latter was about to fight Azumarill until they stopped, but Meganium tripped Bulbasaur and they both started to fight. Luckily, Harrison used his Miltank's Heal Bell to calm all of them down. During Vincent's battle against Ash, the former sent Meganium as his last Pokémon against Bulbasaur. The two sides collided using Razor Leaf and Vine Whip, but Meganium managed to lift and toss Bulbasaur away.
Meganium went to use Body Slam, but missed and got hit by Razor Leaf. It went to use Vine Whip, to which Bulbasaur used its Vine Whip to lift itself up, but got struck by Meganium's Razor Leaf. Meganium went to repeat using Body Slam, but Bulbasaur tossed it away with Vine Whip. The two sides fired Razor Leaf, after Bulbasaur went atop of Meganium. The two sides were quite exhausted and hurt, but pushed themselves to pull one another with Vine Whip. To finish the battle, both Bulbasaur and Meganium fired Solar Beam, ending the match in a draw. However, after the battle, Bulbasaur and Meganium became friends, ending their hostilities.
|Solar Beam||grass||The Legend of Thunder, Part 3|
|Light Screen||psychic||The Legend of Thunder, Part 3|
|Razor Leaf||grass||GS152: Tie One On!|
|Vine Whip||grass||GS152: Tie One On!|
|Body Slam||normal||GS152: Tie One On!|