Pikachu is an Electric type Pokemon introduced in Generation 1.
It evolves from Pichu when leveled up with high friendship and evolves into Raichu when exposed to a Thunder Stone. However, the starter Pikachu in Pokemon Yellow will refuse to evolve into Raichu unless it is traded and evolved on another save file.
Pikachu is popularly known as the mascot of the Pokemon franchise and a major representative of Nintendo's collective mascots.
1) Pikachu is a combination of ピカピカ pikapika (onomatopoeia for sparkle) and チューチュー chūchū (the sound of a mouse squeaking).
2) The nation of Niue released a one-dollar coin with its coat of arms on one side and Pikachu on the other to promote the Pokémon franchise.
3) Pikachu is the only core series starter Pokemon with a pre-evolved form, though Pokemon Yellow predates Pichu.