Before you get on me about the obviousness of Rex, the girl dinosaur, being pink and Meow Meow the cat being blue, you should know that Meow Meow is also a girl.
Here are a few sketches. The far left is the first drawing of Meow Meow and Rex that wasn’t just a square and a triangle. Rex was originally going to be a tiny dino, but where’s the fun in that. The one on the far right is fun, but perhaps a little too Pinky and the Brain. I don’t want Rex to be a dimwit, but I do want Rex to be fun loving.