A bit of a surprise for winter 2020!
It's a Mighty the Armadillo action figure! He is showing up along with the 2nd ...ish wave of the 5 or so inch 'figure and accessory' ones. (If you're counting waves by what's pictured on the box-backs) Notice how they keep releasing Sonic & Eggman over and over while just changing the thing they come with per line.
Mighty is, of course, classic so he appears smaller than the other figures / shorter. There is still no modern version for him, so his is also the only box that will have neoclassic art on it to match his look. He comes with a ring monitor accessory. It looks like one hand may be a fist, or able to hold something. He has 11 points of articulation, and so is thus missing the elbows like all the JP figures (except Eggman) are. The others that are supposed to be out with him are Super Sonic, Sonic with purple chaos emerald and Eggman with Star Post marker.
Fan reviews say that the head of all of these figures is made of a very heavy solid plastic. It's good for quality but less ideal for posing because it makes them easy to tip over.