Stated from the website;
1) We’re going to pick 3 Autobots and 4 Decepticons. Those with the highest number of votes win.
2) Let’s avoid the main characters that have already been featured. This includes:
• Optimus Prime • Megatron • Bumblebee • Ironhide • Jazz • Starscream • Thundercracker • Shockwave • Soundwave • Trypticon • Metroplex • The Dinobots (Grimlock, Slug, Sludge, Snarl, Swoop) • Omega Supreme • Unicron (we have bigger plans for him) • Rodimus / Hot Rod • Ultra Magnus • Galvatron
3) No Triple Changers, Six Changers
• Examples: Astrotrain, Skorponok, Sixshooter, etc.
4) No combined-form of Combiners or combined Duo Changers (though we can use the individual characters)
• Devastator, Predaking, Bruticus, Fortress Maximus etc.
5) Make sure they are from the G1 universe, the cartoon, movie and comics are all fair game!
6) The final list is subject to Hasbro’s approval