Firstly, no need for Mr. :P
Secondly... Generally, if the story is pretty much the same, a hack would fit in the Sideshow Showcase. If the maps are drastically different, there is of course some ambiguity as to where it should be posted, but if the game is ultimately "FireRed Version with edited Pokemon and some new/edited maps", then the Sideshow Showcase is probably your best bet. :)