Lifevirus: OMG, TF2 humour on a PKMN forum. TF2 FTW!
...and I just lost the game...
As for Heavy hitting, I doubt I can get anyone to get up a Heavy costume around here. If I went over to OSU, that'd be a different story. But I believe I'll probably be over toward where I'm currently living instead of that direction. Have you seen some of the cosplayers who get enough people together for pretty much a full TF2 team? Those people are nuts. Some people even make accurate "scale" models of the Heavy gun. it's seriously amazing.
Anyway, back to Halloween costumes...
Gengar, easy outfits are not hard to come by. Zombie has become increasing popular and pretty much takes an existing wardrobe plus a little makeup investment and know-how. If ya don't wanna go that rout, obscure Cardboard outfits would be my next choice. Cut out a giant circle from a packing box and paint in black. Boom! Instant Record. Just pick you favorite obscure 60s band and paint the name of their best album on the center and you're set.
Hope your search is going well.