You can't, it needs a Thunder Stone.
thunder stone
Pikachu and Eevee both need a Thunder Stone to evolve.
Use a thunder stone
Pikachu will evolve into Raichu when given a thunder stone. If you mean Ash's Pikachu, then it very unlikely he will evolve his Pikachu, as Pikachu is the Pokemon Franchise's mascot.
Give Pikachu a Thunder stone and it will evolve into a Riachu. But in Pokemon Yellow, the Pikachu will not evolve. You can get thunder stones easy by mining them in Pokemon diamond and pearl but in soul silver and heart gold you need to buy them with athleet points at the athleet shop
a thunder stone can evolve a pikachu. pikachu won't evolve on it's own.
PIKACHU
eevee and pikachu.
thunder stone
In sunyshore city. I don't no where in sunyshore.
Pikachu and Eevee both need a Thunder Stone to evolve.
Use a thunder stone
pikachu
Pikachu Can't Evolve Without The Thunder Stone.
It is in Sunnyshore City near the lighthouse.
Pikachu will evolve into Raichu when given a thunder stone. If you mean Ash's Pikachu, then it very unlikely he will evolve his Pikachu, as Pikachu is the Pokemon Franchise's mascot.
Give Pikachu a Thunder stone and it will evolve into a Riachu. But in Pokemon Yellow, the Pikachu will not evolve. You can get thunder stones easy by mining them in Pokemon diamond and pearl but in soul silver and heart gold you need to buy them with athleet points at the athleet shop