If you decide to go with Discharge, try to pair your Pikachu/Raichu with a Ground-type or a Pokémon with Volt Absorb like Lanturn to avoid hitting your partner Pokémon. Also, TM Thunderbolt is available in the current version, but it's hidden behind a very frustrating puzzle in the late part of the game. So if you decide you prefer Thunderbolt over Discharge, there's an option to change it later on.