To combat some of the spam bots, forcing someone to select an avatar would be a human requirement and thus reducing spam by spam bots.

vB4 Select/Upload Avatar on Registration Mod

Features:
- Enable/Disable the Mod
- Set an Avatar Category ID to display avatars from
- Allow custom avatars to be uploaded
- Chnage the maxwidth,maxheight,maxsize and enable/disable GIFs for custom avatars
- Limit the amount of avatars to show
- Force the user to select an avatar to successfully register (Shows error if no avatar is selected)

vbulletin/forum/php?t=300600