Zeddicuus
Let's see what comes up from others before I post it. What would you make if you had to use three colours(Any three you wanted), your spells could only have a CMC of 2 or less, and the largest creature you could have could be no bigger than a 3/3, that includes anything that buffs it up.
So no rarity restrictions? You could make a kickass build of zoo under those restrictions.
Grim Lavamancer, Tattermunge Maniac, Isamaru, Kird Ape, Wild Nacatl, Watchwolf. Then burn from lightning helix and lightning bolt, removal from Swords to Plowshares and/or Path to Exile. You'd need a crazy expensive manabase to make it work.
If you're not going to go the really cheap route I'm not sure what I'd do. Maybe in a while I'll have somthing.
EDIT:
Zeddicuus
that includes anything that buffs it up.
Does this anything include the creature's abilities?
How about creatures with a power or toughness of *?
Also, how are X spells counted? The CMC of X = 0 when not on the stack.
How about cards that put creature tokens into play or cards that become creatures?
Depending on the answer to those questions, a build of threshold based landstill could work well.