Uncle Mario Bros. is a likely fan-made or unofficial game for the NES, given the unusual title. It's highly improbable it's an official Nintendo release.  The gameplay would probably involve platforming and potentially borrowing elements from the iconic Super Mario Bros. franchise. Without more information, details on the game's developer or specific mechanics remain unknown. It is likely a ROM hack or homebrew title.

Uncle Mario Bros.

Ultraman Club 3 (Japan)