The Pichu Brothers first appeared in Treasures Aplenty! while Lexi and her friends were on Knot Island at the Treasure Beach. They were both causing mischief on the beach, resulting in Lexi trying to stop them. When they are finally calmed down, Lexi decides she likes their battling attitude and decides to capture them. Unlike most Pokémon, they stay in the same Pokéball. They can be told apart as one Pichu is shiny, while the other has a spiky ear.
Both Pichu are hyperactive and sociable, being very childlike. Because of their immature nature, they don't really enjoy battling other than when playing around. Even as twins, the two are extremely alike in every way.
Due to being so young, their individual skills have yet to come into themselves. However, they can every now and again jolt people and Pokémon without even meaning to - this is heightened when they rub their cheeks together.