Originally Posted by Pe2k Rules
The avatar is the image that will appear next to your name in your posts. By going to the Edit Avatar in your User CP, you can enter a URL of the image, or if you have the image on your computer, you can upload the image you want to use. Maximum size for avatars: 100 by 100 pixels and 40KB.
You can't use the Animated Houndoom sprite because it's 49.2 KB and therefore, over the file size limits for avatars here. I assume Gelatini's avatar works because the Vanillite animated sprite is of a smaller KB Size or Site Staff get special avatar priveliges.
The Houndour animated sprite in the sprite resource is within the limits, so you could use that if you're a fan of the Houndour, as well.