【Updated: 】
Bob-ombs only
Only Bob-ombs, Bob-omb Cannons, Double Bob-ombs, and Giga Bob-ombs appear.
Shells only
Only Green Shells, Red Shells, Bowser's Shells, and Triple Green Shells appear.
Bob-omb Cannon, Double Bob-ombs, Giga Bob-omb, Bowser's Shell, and Triple Green Shells only appear for the drivers who have these items in their special skills.