Gauge is not important. Use the correct hook size for the yarn you are using. I used DK and a 4mm hook and they are roughly 12” including top of hat for Santa and about 9” Mrs Claus.

Notes – I slip stitch and join my rounds and then crochet back into the slip stitch to create my first stitch. When changing colour, I join in the last step of stitch previous. These are my preferences you can do it however you normally do your crochet toys.
I haven’t included how to do a pom pom for the top of Santa’s hat. There are plenty of tutorials out there for these