From the Super Mario Wiki
Mike's Theme (known as Mike's Song in the Super Smash Bros. series) is a song that plays during Mike's opening video in WarioWare: Touched! It is sung by Mike and Sal Out. Not counting the Mona Pizza souvenir, whose song derives from WarioWare: Twisted!, Mike's Theme and Ashley's Theme are the only songs in WarioWare: Touched! that have lyrics.
Like Ashley's Theme, an arrangement of Mike's Theme is featured in Super Smash Bros. Brawl and Super Smash Bros. Ultimate in Japanese and English. It was arranged by Masafumi Takada, with the English vocals provided by Terry Lauber and James Cowan, and the Japanese vocals by Jun Fukuda and the Grasshopper Manufacture sound team.
Mike's Theme and its Japanese version return as a record in WarioWare Gold.