Hold R and press Start, Select, L, Select, Start at the main menu. The phrase ''Oh joy'' will be spoken to confirm correct code entry. All hidden characters, tracks, cups, and difficulty settings will be unlocked.
Play As Plankton
Win Cup 3 under the medium difficulty setting.
Bonus Tracks
Win Cup 1 under the easy difficulty setting in cups mode to unlock the Race Madness, Bikini Bottom Blowout, Safari Speedway, and Bever Fever tracks in cups mode. Win Cup 1 under the hard difficulty setting to unlock the same tracks in time trial mode. Win Cup 2 under the easy difficulty setting in cups mode to unlock the Nearburg Rally, Gritty City Circuit, Pickles Parkway, and Congo Bongo Bang Up tracks in cups mode. Win Cup 2 under the hard difficulty setting to unlock the same tracks in time trial mode.