The Pokemon Pikachu evolves by using the Thunder Stone item, not by leveling up. Pikachu itself evolves from the Pokemon Pichu by increasing Pichu's Happiness quotient.
Also known as the Mouse Pokemon, Pikachu is an Electric type Pokemon that is number 25 on the National Pokedex. Its special ability is Static, which gives it a 30 percent chance of inducing Paralyze on opponents who use attacks that require for it to make contact with Pikachu. Its hidden ability Lightning Rod, on the other hand, makes it immune to Electric type attacks and raises its Special Attack by one point.
Pikachu has a total base stat of 320 with 35 HP, 55 Attack, 40 Defense, 50 Special Attack, 50 Special Defense and 90 Speed. Once Pikachu evolves into Raichu, its total base stat increases to 480 with 60 HP, 90 Attack, 55 Defense, 90 Special Attack, 80 Special Defense and 110 Speed.
Defensively, Raichu is particularly resistant to Flying, Steel and Electric type attacks, while it is particularly weak against Ground type attacks. An ideal moveset for Raichu will be the combination of the attacks Nasty Punch, Thunderbolt, Hidden Power Ice and Encore or Focus Blast while holding the item Life Orb. Another good moveset for Raichu is Substitute, Focus Punch, Encore or Grass Knot and Volt Tackle while holding the Leftovers item.