To be specific on Shinji Ikari comment, use your game boy version on Pokemon Stadium 2 with the Pokemon you need to relearn a move as a team member and face off against the Gym Castle's Elite Four and Champion (don't use it as a regestered team), when you win, Lance will offer to let you have one of your Pokemon to relearn one of its forgotten non-TM taughted moves, such as AeroBlast.