really tough sell!!!
Creative is 100% right... animation featues ae harder to sell than historical epics, believe me I have written both. I have written 4 feature length animations only because I like writing them, and it's good practice, but selling them... you better have a super man or woman agent even if its really good, first, they cost a lot to make even before you add "A" list voices to it. But if you like to wrrite, and you should, go for it, and just write it like a standard sceenplay.
Lots of luck on the sell, if you find a buyer send them my way ha! KD
sorry for spelling my keys are sticking