Its pretty difficult to make suggestions for what to nominate when I've no idea of your interests. What I would suggest is to something unique and different to the usual crop of stuff that gets in. Picking something 17th in the Mario hierarchy and a random pokemon are very easy to pin since we've seen several from their series before.
If you're happy with a round 1 filler character because its someone you like then thats an ok route to go down. The alternatives is doing something interesting for the contest with your nomination. Something that potentially has a high ceiling like a Dark Link, Metal Sonic or a Red XIII, something that brings joke value or something that we've just never seen before and nobody has a clue what it'll do.
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Smurf, the cream of Sonic fanboyism