“I'm 18-Volt. My hobby is music! Check it out!”
18-Volt is a major human character in the WarioWare series. He is a great friend of 9-Volt, and shares his love of video games with him. 18-Volt debuts in WarioWare: Twisted!, where he becomes a new student at Diamond Elementary.
 WarioWare series
 WarioWare: Twisted!
18-Volt is the only new employee of WarioWare, Inc. introduced in WarioWare: Twisted!. On his first day at Diamond Elementary, the teacher asks him what his hobby is, to which he responds by taking out his boom box and playing loud Rock 'n 'Roll music.
18-Volt gets in trouble for this and after school he heads for his house, depressed. However, 9-Volt stops him and states that he enjoys 18-Volt's music. The two of them become fast friends and he invites him over to his house. When they get there, 18-Volt was ecstatic to see that 9-Volt had a Nintendo Entertainment System and the duo spends a lot of time on playing on the system. Eventually, his mother, 5-Volt tells her son and his new friend to cease.
 WarioWare: Touched!
In WarioWare: Touched!, 18-Volt and 9-Volt head to the Toy Express to get a copy of the coveted, new Nintendo GameCube game, 36-Volt Man. 9-Volt snatches one and shows it happily to 18-Volt, who is carrying his boom box on his shoulder. The two friends quickly return to 9-Volt's house, curious about their new game. On their way, they pass the alien Orbulon who is running after his flying spaceship.
At the house, 18-Volt and 9-Volt play far into the night and reign victorious in the game. To celebrate their success, 9-Volt spreads records again while 18-Volt dances behind him with his boom box, but it gets so late that the two gamers fall asleep.
In the morning, when they wake up, it's already 9:00 AM. 18-Volt and 9-Volt are shocked about the fact that they're late and rush to school.
 WarioWare: Smooth Moves
18-Volt visits 9-Volt again in WarioWare: Smooth Moves. There, he shows a Game & Watch handheld console to his tall friend and plays with it. 18-Volt firstly mistakes it for a Nintendo DS Lite. He wants to see more of the console and grabs it. 9-Volt also still holds the console and informs him that he is still playing, but he couldn't wait and tugs on the Game & Watch, but 9-Volt tugs on the other side of it, which causes the Game & Watch to break into two halves. He gets furious and commands 18-Volt to leave his house.
18-Volt has a bad conscience and tries to find a new Game & Watch for 9-Volt. He first looks in Toy Express, but they didn't have what he desires. After departing from the store, 18-Volt notices another store where some gamers lineup. He gets into the store and the owner of the shop, Shop Manager Iwata, coincidentally has the searched Game & Watch on offer. 18-Volt reaches for it, but surprisingly, 9-Volt does the same. The friends face each other and they both excuse each other for their mistakes. 9-Volt tells 18-Volt that he will always be his P2 (Player 2) and all goes well after that.
 WarioWare: D.I.Y. Showcase
In WarioWare: D.I.Y. Showcase, 18-Volt now has his own set of microgames, in which he stars in a game called Jet 18Volt, similar to 9-Volt's microgame set in WarioWare: D.I.Y.. In a bird's eye view of Diamond City, 18-Volt flies in mid-air and shoots an army of Fronks that join together to form the number of the score. His microgames share the same theme as his, which is Nintendo.
After 9-Volt left WarioWare, Inc. to work for Diamond Software, 18-Volt, who continues working for Wario, appears to view him as a rival after his departure, as suggested by his role as a boss in his game (as well as their interaction after the boss game is completed) and his greeting to the player where he insists that he works at "twice the power as that other guy you might be thinking of".
 Game & Wario
18-Volt returns in Game & Wario once again alongside 9-Volt. He holds his own mode in Gamer. In their story, 18-Volt and 9-Volt are playing their new console, and 18-Volt burst into tears when 9-Volt gets a score higher than his. 5-Volt takes the console and orders them to do their homework. They do so, but get mad when find out she got a score higher than both.
He holds a mode in Gamer. He plays microgames on the console, but unlike 9-Volt his mode is timeless and with no interruptions.
9-Volt and 18-Volt come with their own set of microgames in all games of the WarioWare series between WarioWare: Twisted! and WarioWare: D.I.Y. Showcase. For the two previous games and in WarioWare: D.I.Y., he develops his games solo. However, it isn't known how much he shares in the creation of the games. For example, in WarioWare: Touched! 9-Volt says "our games", but in WarioWare: Twisted! he just speaks about "my games" in the character select menu, plus 18-Volt isn't even mentioned by name in the menu.
The microgames are based on products of Nintendo, mainly on game software and hardware, but also on merchandise from the time before Nintendo became popular as a video game company. Microgames based on the Mario series are featured in every WarioWare game.
In WarioWare: Twisted!, the microgame set of 9-Volt and 18-Volt is called Spintendo Classics. All microgames are only based on Nintendo Entertainment System games in this game. While the microgames of most of the other developers involve a particular style of gameplay per developer, the microgames of them require all kinds of spin techniques.
In WarioWare: Touched!, the name of 9-Volt and 18-Volt's set of microgames is Retro Action. The choice of Nintendo products is much more versatile than in the prior game again. Also newer products from the 21st century are featured. The microgames include a variety ways of using and also the application of the microphone, while most other microgame sets involve a particular technique again.
In WarioWare: Smooth Moves, 9-Volt and 18-Volt's set of microgames involve all possible forms. Considerably more microgames are based on more recent Nintendo products. An example is Brain Age, which is based on the Nintendo DS game Brain Age: Train Your Brain in Minutes a Day!
In WarioWare: D.I.Y. Showcase, 18-Volt goes solo and has created a separate set of Nintendo themed microgames, while his friend 9-Volt goes solo for the first time since WarioWare: Mega Party Game$, in WarioWare: D.I.Y.
 Official Profiles and Statistics
 Website Bio from WarioWare: Touched!
Old-school Fan-boy finds a soul-mate in new classmate 18-Volt. Together, they serve up microgames inspired by classic Nintendo games.
 Super Smash Bros. Brawl Sticker Information