From Sonic Retro
Mighty: A Sonic Clone?
However, careful observation proves that Sonic may not be entirely absent from this game. Mighty the Armadillo is one of the available characters in Chaotix, and while playing as him, you might notice that he seems... familiar.
And indeed, he does! Nearly all of Mighty's poses match up with Sonic's poses from Sonic Crackers, and occasionally Sonic CD. You'll also notice that some of the unused poses in Crackers match up with some of the poses Mighty uses in Chaotix!
Amy in Chaotix
Amy is an "unlockable" character in Chaotix! Actually, she's just an extra for the sound test screen. Still, that's cool, right?
Input the following code at the color select screen to "unlock" Amy:
And she'll appear right on the sound test screen:
COOL SWEET & CATCHY!
Through unlocking the level select, you can access an unused, removed character from the game. Here's the code for the level select (input on the color test):
(This code will also unlock debug mode, which works exactly like the debug mode in Sonic Crackers)
From there, you can access the stage select:
And inside the stage select...
...we can select our new character!
As you can see, it's just a garbled version of Knuckles' sprites with Mighty's palette and moveset. Nothing special.
However, it is generally speculated that this is the character slot in which Tails originally was, in Sonic Crackers. The leftovers are a result of random, undefined data strings, giving the character nonsensical statistics and properties.