The THIRD paragraph (you didn't even need to scroll to start reading it) ...
You may add a custom avatar (also called a "author icon") to your profile. It should be no more than 64x64 pixels in physical size, and no more than 20KB in data size. It should not contain any offensive graphics or needless animation, and you agree to remove or change your avatar if requested by a moderator. Planet GameCube Forums reserves the right to remove the avatar feature at any time if it is deemed to be causing problems with page loading times, or causing unnecessary strain on server resources. Use of images in your avatar falls under the same rules as linking to any image in the Forums ... they must be hosted on your own personal webspace, and should not be linked to any other site's bandwidth without their knowledge. Violation of this rule will result in your being banned from the Forums.