The Walt Disney Company, or Disney for short, is a American global multinational entertainment and media conglomerate headquartered at Burbank, California, at Walt Disney Studios. Mickey Mouse, created by Walt Disney, is the mascot of said company for years. This company has a history with Nintendo, as they had collaborated with one another on multiple occasions.
Involvement with Super Smash Bros.
Sora, the main protagonist of the Kingdom Hearts series, was confirmed as the final DLC character in Super Smash Bros. Ultimate on October 5th, 2021. This is mainly because Disney, despite not developing or publishing the Kingdom Hearts games made by its partner company, Square Enix, is the owner of the entire franchise, thus being credited for Sora's inclusion.
The keychain on Sora's Keyblade is the only reference that represents Mickey Mouse.