If you have an emulator that supports Game Genie codes chances are it supports PAR codes as well. Game Genie and PAR allow a player to patch the game with special codes that can do anything from screw up the game to allow special abilities not normally found in the game.

Imagine being able to morph into your favorite creature on any level. A member of DARK SEA went through the trouble of digging up such codes and made them available to the public. The codes alter variables that can change Ecco into something else, some of the transformations like the Vortex Drone require an additional code to display correctly.
The codes are a bit buggy, the a Vortex Drone requires certain colors to be present in order to display right. The Vortex Drone has its special ability along with its weakness of not being able to handle the pressure when it swims to the waters surface.

The most complicated to get working code is the one that transforms Ecco into a Sea Gull. It will work only if you jumped out of the water on a rock above the waters surface and bounced off of it. If your quick enough to pause the game after performing this action then you will be able to control the Sea Gull.
The Sea Gull doesn't work on most levels, most of the time it dies upon transformation and you must activate the Dolphin code to force Ecco to change back. I've only tested the codes, I haven't discovered any tricks to make the Sea Gull stay transformed.
FFAA12:0000 - Use this code if something goes wrong to change Ecco back into a Dolphin. If your using the Sea Gull morph you will need this code entered in and ready to activate.
2. Morph into a JellyfishFFAA12:0001 and FFAA78:1850 - Requires the first code to make Ecco act like a Jellyfish and another to make him look like one. Make sure the Jellyfish isn't anywhere near the waters surface otherwise it will attempt to change back into a Dolphin.
3. Morph into a SharkFFAA12:0002 - When activating this code the shark might bounce of screen, just keep moving the shark until the screen regains focus. Some levels are not ideal for a shark, an interesting feature of the Shark is that it will eat anything.
4. Morph into a Sea GullFFAA12:0004 - This code only works on certain levels, after bouncing off a rock above the waters surface, pause the game then activate this code. It is very hard to get this code to work correctly on the Vortex Future levels.
5. Morph into a Vortex DroneFFAA12:0006 and FFAA78:491C - Requires the first code to make Ecco act like a Vortex Drone and another to make him look like one. The Vortex Drones colors are dependent on certain levels palettes.
Related: Sega Genesis Emulation