Here is the recent addition to my Nega-Mega Evolution series, with this being the first one I've done in color. While it was difficult to come up with this design, I knew I wanted to use Gyarados for this milestone since, as I mentioned in my premise, Nega-Mega evolution combines Mega Evolution with the evolution inducement wabes from Gen II that resulted in the Red Gyarados, so I thought it'd be fitting to use the same pokémon to help show off this transformation.
When designing Nega-Mega Gyarados, the main area I tried to focus on was the mouth since I wanted it to look even more ferocious and terrifying than it usually is, plus Gyarados' large open mouth is usually the first thing that people think of. Because of this, I decided to have its mouth look like a regular sea serpent's face, but then once it opens up it would look like a monstrous sea creature with tons of teeth, similar to something you'd find in mythological stories like The Odyssey.
While looking at dragons and sea serpents for the design, I was looking at leeches and other fictional creatures to come up with the mouth such as a Graboid, a Tatzelwurm, and the sandworms from Beetlejuice. As I was drawing the rest of the body, I wanted to turn the dots on Gyarados' body into spikes to look more terrifying, plus I had the phrase "Teeth and Spikes, and Teeth" playing through my head over and over again, so this became the result.
For the color scheme, I chose blue for the base body tone to go with its natural appearance, and then I used three colors that the series usually associates with Dragon types (purple, turquoise, and sky blue) to show its type change. Lastly, I mentioned Defeatist as its ability since I thought this would represent how Nega-Mega evolutions go beyond their natural limitations but drain their strength and life force quicker in the process
P.S. Sorry for re-uploading this, but I noticed my last scan had a coloring error, so I wanted to fix it