Pikachu - Raichu. Eevee - Jolteon. As of the IV generation, only two Pokemon will evolve if exposed to a Thunder Stone: Pikachu into Raichu and Eevee into Jolteon. Despite the number of Electric-type Pokemon, only these two require a Thunder Stone to evolve. pikachu- evolves into raichu. eevee- evolves into jolteon.