|First Appearance||WarioWare: Twisted!|
|Latest Appearance||Game & Wario|
18-Volt appears in WarioWare: Twisted! as a new employee of WarioWare, Inc. He quickly becomes friends with 9-Volt after he gets in trouble when he plays rock music in class, which 9-Volt enjoyed. 9-Volt is invited to 18-Volt's house not long after they met, where they discover their mutual love of video games (in particular the NES).
In WarioWare: Touched!, the friendly duo of 9-Volt and 18-Volt head to the Toy Express to secure a copy of the new GameCube game, 36-Volt Man; this is quickly snatched up by 9-Volt and taken back to the house. They play late into the night and dominate the game, celebrating their success with music and dancing. The next, the friends woke up late and had to rush to school at 9:00AM.
WarioWare: Smooth Moves
Once again, 18-Volt and 9-Volt continue their adventures in WarioWare: Smooth Moves. When 18-Volt is visiting 9-Volt at his house, 9-Volt shows his friend a Game & Watch system. Impressed, 18-Volt mistakes this for a DS Lite and attempts to take it from him. Because he is still playing, 9-Volt holds onto the system and the opposite forces end up breaking the Game & Watch in two. Eventually, the two make up when 18-Volt tries to fix his mistake by buying 9-Volt a new system.