This is a racing game where it's a crossover. Here's the list of characters and their vehicles.
The Doctor-The TARDIS
Sonic-His car from SaSAR
May-Sploder hating tank
Head-Sploder hating tank
MINI GODZILLA-KAIJU KAR
Yoshi-The yoshi egg kart thingy from Mario kart DS and 7
Mermaid Man-The Invisible Boatmobile
Random Guy-A car
GIANT GODZILLA-He is the best character in the game. He doesnt need a kart.
Poostudios-His car from the Sploder game "Poostudios Car"
Tails Doll-SUNSHINE CAR
GREAN HIL ZOWN
London (Doctor Who)
Green Hill Zone
Cemical Plant Zone
Post Apocalyptic Sploder
Sploder (represents every sploder member)
A stage from Shadow the Hedgehog
Place where they make cars