What would be your ideal worm–>cocoon–>some kind of winged thing line?
I don’t really have an “ideal” one, in the sense that there’s something in the back of my head that would work really well for it, but if you really wanted me to do the whole caterpillar/cocoon/butterfly thing, then I guess I think it would be really neat to do something with the Atlas moth. You know, this guy:
As it’s one of the biggest moths in the world, as well as named after the titan who holds up the sky, we have an excuse to do some somewhat unconventional things with it, like allow it to learn Fly and make it a big physical bruiser instead of special attack and support. Maybe have it punch things with six arms at once. I want to do something with the false snake heads on its wing tips too, but as tempting as it is, I worry that giving it actual snake heads that bite opponents is probably a bit too weird for something that traditionally would go in an early-game slot, and probably make the design too complicated and crowded. Possibly just give it the ability to use Glare and be done with it.
Atlas caterpillars and chrysalises aren’t all that exciting to look at, so it’s probably best to take a bit of artistic license with them, and fit them in with however the final form ends up looking.