All versions of Nintendogs have Mario items that you can collect for your dogs. Although some items can only be found in certain versions, you can trade with other Nintendogs owners for the other items.

Based on the Question Block and Mushroom designs from Super Mario Bros., the ? Block and Rubber Mushroom sports items are available in all versions. Also available in all versions are the Red Hat and Green Hat accessories, which are Mario and Luigi caps that your dog can wear.

Each version has one toy kart from Mario Kart DS. Chihuahua & Friends has a Bowser Kart, Dachshund & Friends has a Mario Kart, and Lab & Friends has a Peach Kart. While you're driving these karts around, theme music from MKDS plays in the background.

The Chihuahua & Friends version has a "Mario's Theme" Box, which is a music box that plays the Super Mario Bros. theme as you spin its crank with the stylus.