From Sonic Retro
Information About **********
The character is referenced on the level select screen as "**********". PACHUKA coined the term "Wechnia" by combining the words "white" and "echidna". It was hypothesized that Wechnia was originally Tails at one point, since he is listed second on the level select after Mighty. This was later confirmed with the release of the Knuckles' Chaotix 1207 prototype, the ROM of which features a life icon for Tails, as well as a palette consisting of colors similar to his Sonic Crackers appearance. In addition, the character also has the ability to fly and tire after a while exactly like Tails until the 0111 prototype; in later prototypes and the final, Wechnia uses Mighty's wall kick rather than flying. Further evidence that Wechnia is Tails is that if he has chosen as the partner, you are automatically given Mighty, who of course was a sprite swap of Sonic.
To play as or have Wechnia as a partner, go to the Options menu and select "Color Test". Three pairs of 00 should be surrounded by <>. Hold and press until the first pair is 06. Release , hold and press until the second pair is 0B. Release , hold , and press until the third pair is 11. Now release and press . Three pairs of 04 should now be highlighted. Hold and press until the second 04 is now 00. Release , press , then proceed to the main menu. The option "Stage Select" should now be below Options. Select it, then chose your character or partner as **********. You will have Wechnia, but once he touches the ground, the game will crash unless one of a few certain levels are selected. Even then, the game can crash if certain triggers occur, such as being harmed.