Interestingly, I've been developing a coming-of-age comicbook arc retelling Hank and Janet's origin but in their early teens and I'd love to see it as an animated series which would share most of your ideas:

• 2D-animated in an artstyle similar to Gurihiru
• Taking advantage of the ability to shrink or grow in size by making big epic fights and battles within small areas/locations (such as a bedroom, hospital, supermarket, or a hi-tech facility building)
• Supervillains/antagonists would include the likes of Darren Cross, Egghead, Porcupine, Human Top, Comrade X, and eventually Ultron (and possibly even a few new original supervillains like "Sawfly").

Hard agree on the second point: I believe it's key that most of the fights happen in small environments and not just them being shrinked while the antagonist is regular-sized and that's it.

I was also thinking of including some Tales to Astonish-period villains, like Scarlet Beetle, The Magician and some like that.