I get what you're saying. No, Bitey won't be a cutout puppet in the future, but yes I've used some puppet segments for him here. The only reason is entirely because there's so much slow motion in this teaser. You seem to know a bit about animation so you probably know how difficult (and rare) slow motion is in hand drawn frame-by-frame 2D. And there's no way I'm animating 25 seconds of a character in slow motion by hand. If this was action at normal speed (like the Yuyu movie), it would be fbf all the way.

Hopefully you noticed Bitey's hair and the non slomo parts (when Bitey first runs in, and the witch's cloak) which are all meticulous fbf :P

Having said all that, I'm not the world's best character animator and even in my old Flash stuff I was using tweens and morphing wherever possible to speed things up -- an example here is Bitey's hair. It's about 15 different fbf "tufts" looping at different speeds and lengths. Looks a little bit cheaper, but it's much quicker and easier than animating all that semi-slomo hair on singles.