I have been following along with Truegreen7's series on Youtube where he and 3 other Fakemon artists get together to design a new pokemon based on the same prompt.
This Prompt was: Normal to Abnormal

The first evolution Gleesh is based on a Leptocephalus the Larval from of an Eel which tend to be Transparent, Bony, and a little spooky looking so I decide to go with the type Water/Ghost. Fun Fact: For a long time people in Europe didn't believe eels were able to breed? Turns out European Freshwater Eels make a long trek out to somewhere in the middle of the Atlantic Ocean even crossing land for up to 3 days in order get to the Ocean. People had known about Leptocephaluses for a while but it wasn't till a man kept one in a tank and suddenly realized it turned into an eel that he discovered they were baby Eels. The question of how Eels reproduce particularly puzzled the Greek Philosopher Aristotle, who came to the belief that Eels didn't breed at all, his theory was that Eels spawned from Horse Hair that fell in the water.
Lesson of the day: Don't listen to Aristotle, he may have been an influential Philosopher but he was also a moron and was wrong about a lot of things

The Second evolution Rhibboa is based on the Ribbon Eel, a species of Moray that comes in a unique color of Yellow and Blue and has and appears flat as a ribbon. It also has a unique life cycle being a Protandric Hermaphrodite: All of them are born Male and then as they grow they transition into being Female, so as a pokemon the first evolution is 100% Male and then when they Evolve they are 100% Female and the evolved form changes from Water/Ghost to Fairy/Ghost.

Gleesh = (Glass + Eel backwards + Fish)
Rhibboa = (The scientific name of the Ribbon eel "Rhinomuraena quaesita" + Ribbon + Boa as in a Feather Boa that you wear around your neck as opposed to a Boa Constrictor snake, but also as an Eel it's very Snake adjacent)