The more the merrier and you don't need any animation or drawing skills tbh.
I'm running a collab where each person draws a single frame (or more if you want) by tracing an image from my pre-rendered "default" animation.
Here's the google drive folder with all the frames. Choose a frame that hasn't been redrawn or renamed, draw over it, then replace the old file with your new file. Add _yourname to a file to reserve it (e.g. 00022_cyansandwich).
You can see some redrawn frames in the drive as examples