Wait is every drawing here Baxter's? Are there no in betweens?

Yeah, as far as I know he animates everything on 1s by himself.

Edit: Looking at the numbers, every circled number is a keyframe and uncircled numbers are inbetweens. Some of the keys are noted as "major keys" (also called "golden poses"), which are the main key drawings to plan the animation. I can't say for sure if he did all the inbetweens or if he had an assistant, but since he was a guest animator it's likely that he did everything.