From the Super Mario Wiki
The Koopa Klub was a soda bar in Crime Land that was owned and operated by Al Koopone during the events of The Super Mario Bros. Super Show! episode "The Unzappables". Aside from being a hangout for various members of the Koopa Pack, it served as Al Koopone's headquarters. After Al Koopone flees from Crime Land, Mario renames the Koopa Klub to Mario's Pasta Palace.
Little is revealed as to how Al Koopone gained acquisition of the Koopa Klub. Regardless, he was content in using the place as his headquarters, as he believed that Mario and his friends wouldn't be able to get inside very easily.
After Al Koopone supposedly drowned Mario and his friends in one of Crime Land's rivers, they prepared to infiltrate the club by dressing up as gangsters. Mouser at first refused to let them in for not knowing the password, causing him to accidentally reveal that it was "cheeseballs". Mario's group was then able to enter the Koopa Klub, where they stole Al Koopone's Unzappable Hats from the coat check room.
While wearing the Unzappable Hats, Mario's group was immune to the Snifit bullets that the Koopa Pack shot them with and managed to defeat them with Vegetables. Al Koopone attempted to flee from the Koopa Klub, but Mario stood in his way, forcing him to escape through a Warp Zone spawned from a Magic Potion. With Al Koopone gone from the Koopa Klub, Mario was free to rework the place into Mario's Pasta Palace, which became Crime Land's first Italian restaurant.