The hardest part was thinking of a Mario-related sprite that fit each category. A cookie to anyone who can point out what game each one is from.
Well, sadly, I can't name all of them, but I am proud that I know most of them. Here we go!..
Poster of the year: I recognize the Starman sprites, but cannot place where they are from. Everything else (the mushrooms, the pipe borders, the tissue paper..) seem to be edited sprites from Super Mario World (the tissue paper being from Yoshi's House, after you beat Bowser). Also, the little badges on each award are edited sprites from SMBDX's badges.
Best Moderator: the Fire Flower is from Paper Mario (I think).
Best Regular: the Mushrooms look like they are from Mario Kart 64 (and/or Super Circuit, since they seem to share various sprites).
Best Newbie: Yoshi eggs are from Super Mario World 2
Topic of the year: Whatever that sprite is is from Paper Mario
Post of the Year: Also from Paper Mario
Best Signature: Paper Mario (Bonus point: It's Luigi's autograph!)
Best Custom Title: Paper Mario (Nice use of the Gold and Silver cards)
Most Amiable: A happy gold coin that a bonus cloud dropped in Super Mario World
Most Average: Green Koopa Troopa from Super Mario World
Cleverest: Lighting from a Mario Kart game (since that is the only Mario game that I know of that has a lightning sprite)
Blast from the Past: Either the Spark partner's body from Paper Mario (without a face), those enemies that looked like Sparks in Yoshi's Island, the Angry Sun from SMB3, or an edited explosion.
Most Missed: an unsprouted flower from Yoshi's Island
Wisest/Most Mature: Frogfucious from Mario RPG
Social Butterfly: Flying Wiggler from Yoshi's Island
Most Improved: an edited MK64 mushroom (edited because there are no 1-Up Mushrooms in that game, or in MKSC)
Most Helpful: the orb that appears after you beat Boom-Boom in SMB3 (from Super Mario All*stars, no less!)
Funniest: Luigi in Peach's spare dress from Mario & Luigi: Superstar Saga
Dynamic Duo: Small Mario jumping/dieing, and small Luigi jumping/dieing from SMB3 in All*stars
WTD Award: Fawful from Superstar Saga
Deezer Award: There's that Starman sprite again.. I
think it's from some form of Mario Kart, as I can't recall a Starman looking like that in any other Mario game.
Do I get a cookie? XD