Help I want to make dragons but I don't know how

I have searched everwhere and I can't find a proper solution to this.

Basically, I want to make ender dragon reskins that have the same abilities as the dragon but in a different color. that's it.

I remember seeing a video on how to do this (they used a blaze as an example instead) but I can't find it so I turned to the forums.

I managed to find an ender dragon model but I don't know which animations go with which body parts and neither do I know how to give it ANY dragon ai so I basically have a still dragon with the ai of a pig and the spawn conditions of a hostile mob.

Please help me!