Ash
Ash Ketchum is a 10 year old boy who set out to become the greatest Pokémon Trainer of all time! On his tenth birthday Ash wanted to begin his journey by choosing one of three Pokémon available to beginners, Squirtle. However, on the morning of this event he slept in by accident and in a hurry, ran to Professor Oak's lab to recieve his Pokémon. When Ash got there he found his three rivals in Pallet City had already taken all three Pokémon! Seeing Ash was worthy of a Pokémon, Professor Oak gave him one called Pikachu. At first Pikachu did not like Ash until the Pokémon was attacked by a horde of Spearows and he saved him. From then on Ash and Pikachu became the best of friends. Their adventures led Ash to meet Misty, a girl who he had stolen a bike from to save himself and Pikachu from the Spearow attack. Ash soon caught other Pokémon such as Caterpie, Pidgeotto, Bulbasaur, Charmander, and the one he originally wanted, Squirtle. None of them topped the friendship he and Pikachu had though. During his travels Ash also met Brock, a gym trainer who he had defeated at the Pewter City Gym. Brock joined the group and the trio set forth into many adventures.
Gary
And of course, every hero has a rival that wants to one-up him every chance he gets. In Pokemon, Gary is the one who wants to be better than Ash. Grandson of Professor Oak, he thinks that since his grandfather's in the Pokemon business he should be the one to claim the title of "greatest Pokemon trainer in the world". He's selfish and egotistical, even having his own group of cheerleaders to root him on in the first episode of the anime ("Gary, Gary, he's our man! Go Gary!").
Pikachu
Pikachu's the cutest of all!!! Yes, he's so cute, he's the animal that appears on anti-cute people's Anti-cuteness Signs! ANYWAY, of course HE has a personality too. He's sortov the master of Pikachus, and you may think that this is just because he's one of the main characters. Not so. He's came from Professor Oak's labratory, meaning he wasn't born in the wild. Professor Oak said so himself that Pikachu does in fact have a small problem. I don't know what this may be, but as Meowth claims, Pikachu's powers exceed even it's evolution stage, so OBVIOUSLY Pikachu's special. Now, on his personality, he's basically just having fun.
