The main issue I find with Tails is not so much that his sprites are unchanged between Sonic 2 and this prototype, but there is a singular difference in regards to the palette besides the obvious one of the change in grey palette. His AIZ underwater palette is much different to the final one in Sonic 3, in part because he shares his palette line with Sonic.

Alas, that makes it wildly difficult to form a sheet for, since it'd be pointless to
1. Make a sheet of already-recorded sprites for the sake of one palette.
2. Make a sheet in which only one pose and the underwater palette are recorded.
3. Include the palette on the Sonic 2 sheet (a severe no-go option).

My best solution is to place it on an Object sheet somewhere. Sure I might have it on the Monitors sheet already but it's better to see it on the character himself, yes?

I get why Tails' sprites aren't added here. He has no new sprites, and the palette is pretty much the same as Sonic 2 though the grays are different

Sonic's standing sprite look weird

neat, it's pretty funny how some of s2's style slipped in the final,

Not a standard thing again, but it became felt that the main page's "Prototype" section would become too stuffy between characters and stage content, so it was easier to copy the logic that was employed for CD's prototype content and create this page.