Gary has been a neighbor of Ash Ketchum
since they were both young. At one time they seemed to be friends and went to see movies together as seen in Lights, Camerupt, Action!
. Before either of their journeys began, both Gary and Ash found an old Poké Ball
while fishing. The two boys began fighting over who would get to keep the Poké Ball but ended up breaking it in half. Since then, they decided to keep the two separate pieces for themselves. It was revealed in The Ties That Bind
that they still carried the pieces with them.
In the original series
The day he started out on his Pokémon journey, he came off as an arrogant trainer, much like his game counterpart, Blue. His chosen starter Pokémon was Squirtle which was actually the same Pokémon that Ash originally wanted to start with. He even had a group of cheerleaders who cheered him on in all his battles and would go so far as crying when ever he lost. And he didn't walk on his journeys like most trainers did. Instead he had his own sporty red convertible with his own chauffeur. Gary loved when he got a chance to make fun of Ash by bragging about how far behind Ash was compared to him. He also gave Ash the pet-name of Ashy-boy.
Soon he would eat his words when he would challenge the Viridian City Gym Leader, Giovanni to a Pokémon Battle for his final, but not necessary, badge in Battle For The Badge. At first he seem to be winning against the Giovanni, knocking out most of his Pokémon. But then Giovanni sent out Mewtwo against the trainer and even let Gary use both his Arcanine and Nidoking against it. Mewtwo made quick work of the two Pokémon and Gary experienced his first (known) loss. However this still didn't change his arrogance. It would take a loss at the Pokémon League in The Fourth Round Rumble during his fourth battle to finally realize that he needed to change himself.
Gary eventually returned in A Tents Situation. Much unlike his former self, he congratulated Ash on his victory in the Orange League. Soon Ash challenged him to a battle with his Pikachu as his choice. Gary in turn used his Eevee. Gary managed to defeat Ash and then left on his journey through Johto.
In his few appearances during the Johto season, he seemed to have become the complete opposite of who he was. He became polite, intelligent, and respectful to others, including Ash. In Can't Beat The Heat! he battled Ash at the Silver Conference. Ash ended up winning the battle when his Charizard defeated Gary's Blastoise.
In Gotta Catch Ya Later! Gary decided that he didn't want to be a Pokémon trainer anymore but instead wanted to be a Pokémon researcher like his grandfather.
In Putting the Air Back in Aerodactyl, Gary works on Sayda Island with Crystal. There, he revived an Aerodactyl from an Old Amber. At first the Aerodactyl was afraid of him and every other person on the island. But it soon gained his trust after he fed it some fruit that Aerodactyl used to eat.
Eventually, he moves to the Sinnoh region where he is currently conducting his research.
In Home Is Where The Start Is, Gary reunited with Ash and battled him with his new Electivire and defeated Ash's Pikachu once more.
Diamond and Pearl
In Ill-Will Hunting! he was taking care of a group of Shieldon and protected them from the evil Pokémon Hunter J and her minions. He appeared once again in DP085 where he helped Ash and Gligar by giving a Razor Fang to Ash which caused Gligar to evolve later.
This listing is for Gary's Pokémon as of Ill-Will Hunting!:
Gary also has more than 150 Pokémon in his collection.