Thread seems dead but I'm posting this anyway.
>1.Poison/Dark or Poison/Flying
Three stages, not sure on the first.
Second stage would be a Maggot with a Hazmat suit theme.
Final form would either be a fly or mosquito. The head should resemble a gas mask.
No need for a picture.
>2.Bug/Ground?
Based on a Green Tree Ant, the gaster should be an emerald stone.
They would be quite rare due to being hunted.
>3.Bug/Fire
Based on the Lord Howe Island stick insect. The latter end of it's body would form into a cannon or gatling gun.
Three stages too, maybe?
http://vimeo.com/14413689>4.Water/Fairy
Based on a Cave Angelfish. Two stages.
I assume designs for this would be obvious but I'm thinking they would be similar to Dratini and Dragonair.
