This hack makes Tails follow Knuckles around like he does Sonic. Simply select a save file with Knuckles and Tails will follow him. Patch this to a Sonic 3 & Knuckles ROM in binary format (.bin or .gen).
There are a few minor issues with this patch:
Other than those issues this plays perfectly, Tails behaves exactly as you’d expect.
Sonic and Knuckles & Sonic 3 (JUE) [!].bin
ROM/File SHA-1: CFBF98C36C776677290A872547AC47C53D2761D6