Unfortunately, Rock/Flying/Fighting screws the Fire Type over in all 3 ways.
Flying: 4x Rock Rock: 4x Water 4x Ground Fighting: FANBASE RAGE
And if you try to do a reverse triangle with the types (as the fourth gen kinda-sorta-almost did), you get Water/Flying (not weak to Grass), Grass/Rock (not weak to Fire), or... FANBASE RAGE! Though if you go in the same direction as the "main" triangle, the failures only happen in the Fire/Fighting case.
Creator of Jay's Journey (see quote!) "It's not ten years old! Therefore, it sucks!" - Nostalgia whores everywhere
I think the reason they stick with the Grass/Water/Fire trio is because any five year old child that gets the game and easily work out that Water beats Fire, Fire beats Grass, and that Grass beats Water. A lot of those other triangles would be harder for someone new to Pokemon (especially if they are young) to figure out.
White FC: 4727 7422 4019 Platinum FC: 2063 5286 9480