18-Volt is a character in the popular game series WarioWare. The character first appeared in the Game Boy Advance video game WarioWare: Twisted! where he was a video gaming fan like his friend 9-Volt.
18-Volt is the only new employee of WarioWare, Inc. introduced in WarioWare: Twisted!. On his first day at Diamond City Elementary, the teacher asks him what his hobby is, to which he responds by taking out his boom box and playing loud 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 it's past his bedtime and 18-Volt goes home.
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 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 spins 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.
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 wants to always be his P2 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 9-Volt's, which is Nintendo.
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 they get jealous when they 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.
18-Volt appears once more in WarioWare Gold. As he is walking along Emerald Street, he notices a sniveling kid on the street and asks what is wrong. The kid tells him that a girl named 13-Amp stole his video games, causing 18-Volt to engage in a rap battle with 13-Amp, under the condition that the winner takes the loser's games. Eventually, 18-Volt wins back the stolen games, and tells 13-Amp to meet him at the playground of Diamond City Elementary should she want a rematch, and walks off, leaving 13-Amp shocked that she was beaten by someone in the fourth grade.
18-Volt also appears in the Potluck Gang set of the Ultra League, where he goes on a camping trip with Orbulon, 9-Volt, Ashley, Red, Dribble & Spitz and 5-Volt. He bring vegetables to the potluck, and is then seen playing cards with the rest of the group.
Rhythm Heaven series
18-Volt makes a small cameo in this game in the Wario...Where? challenge set's Samurai Slice.
Super Smash Bros. series
Super Smash Bros. Brawl
He appeared as a sticker that grant a bonus of +4 attack to any executed with the arms.