@ Otamon: Welcome to Smogon! Anyways, take a Ralts, name it whatever you want. Ralts may only use moves with a BP of 60 or less. To evolve, have it solo (Take out on its own) two Gym Leader Pokémon. To evolve again, have it solo a further three Gym Leader Pokémon.
@ Organization Member XIV & SchnitzelLion: You both get Zapped the Diglett.
Zapped has developed a fear of Electric-Type Pokémon, & may never battle Electric-Type Pokémon as a result. Furthermore, because it does not want to be anywhere near them, let alone hurt them, Zapped may never use STAB moves. Have it solo 20 Trainers to evolve. You may not use the Vs. Seeker to achieve this.
Have fun the two of you!