You basically can enter any robot that has the tag: ev3replica.
BUT, it is recommended that it is a replica of ev3. You can enter more than once. If you have already made a ev3 replica, just add the tag, ev3replica to enter. All entries due April 4th, 2013.
Here is a pic of the real ev3storm.
Here is some pictures of the Ev3 replica I made, NXTstorm, after ev3 storm. If you have any questions, please ask through the comments.
And the winner is.... Ninja Snake by High_Five! I chose this entry because it was explained well, clear pictures, and looked totally awesome. Congrats High_Five!
Thanks to all other contestants who entered. Be sure to check out all the cool features of Mindstorms EV3!