A Pokémon Trainer is a person whose life is dedicated to catching Pokémon and using them in battles. Their goal in life is to capture and train all the Pokémon in the world. They also hope to defeat the Elite Four of their respective league. A Pokémon Trainer appears in Super Smash Bros. Brawl, having Squirtle, Ivysaur, and Charizard as his Pokémon. Squirtle is fast and agile, but can be KO'ed easily reason being that he's lightweight. Ivysaur has many attacks which deal a lot of damage, but his only recovery is a tether. Charizard has many good damaging moves that could have high knockback, but is very slow. His Final Smash is called Triple Finish, where all 3 Pokémon come out and attack. Squirtle uses Hydro Pump, Ivysaur uses Solar Beam, and Charizard uses Flamethrower in their Final Smash. The English voice over is done by Michelle Knotz.
In the first generation of Pokémon, there was only one form of the main Pokémon Trainer which was male. Pokémon Trainer's only had 151 Pokémon to choose from to catch, and the universe of Pokémon wasn't very open to a Pokémon Trainer. The Pokémon Trainer's main focus was to catch many strong Pokémon and train them to high levels, and then defeat eight gyms and defeat the Pokémon League. Raising Pokémon for a Pokémon Trainer in the first generation was considered to be easy unless a Pokémon like Charizard or Gyarados was involved.
The female playable character was introduced in the second generation and trained Pokémon and battled the same way as the male trainer in the original generation. Both males and females alike were very good trainers commonly. There were now more options for Pokémon Trainers. They could now access new locations and were open to over 200 Pokémon, harder to train and catch. The gyms were more scattered around in the Johto region in Generation II, so almost any gym could be accessed first. It was not unlikely to end up battling Clair's gym before battling Bugsy's or another's. The Pokémon Trainers were more difficult by this generation.
In the third generation, the Pokémon Trainer now had more paths to choose then gyms. They could now attend a "Pokémon Contest" and win a ribbon when in a gym (which was also accessible) you would earn a badge. The Pokémon League ended up having two champions at one point, Steven and Wallace. Pokémon Trainers were sometimes male and sometimes female.
The fourth generation had the same options for Pokémon Trainers as in the third. Contests and gyms were active, however, in the Sinnoh region, there was originally only one contest in the games which was found in Hearthome City.
In the recent fifth generation trainer's paths in addition to gyms include Pokémon musicals.
Super Smash Bros.
The Pokémon Trainer appears as a playable character in Super Smash Bros. Brawl, however, he doesn't fight using his own force. He calls on three Pokémon, Charizard, Ivysaur, and Squirtle. The Pokémon fight against the enemy, making him a Generation I character.
In the anime
Pokémon Trainers are found everywhere and train with many different Pokémon. Like in the games, they can only hold up to six Pokémon in their party. Some trainers in the anime will always leave an open spot in their Pokémon party just incase a new Pokémon comes around and they would more enjoy that one in their party. For the most part, Pokémon Trainers are the same as they are in games.