What is the hardest fighting game out there?

[sethnintendo]

NiKKoM said:

Virtua Fighter is the most technical fighter.. hard to learn to be really good at it..
And any SNK fighter before 1996 are the hardest in diffculty.. especially the bosses..

Virtua Fighter 1 was okay and hard to pull off the good moves.  However, button smashers could still beat decent players.  If a button smasher can beat average/pro person in a fighter then that fighter isn't the most difficult.

I believe Smash Bros. is the most difficult to beat a pro at (limited items or no items).  You can't just sit there and smash the controller buttons and win.  A button smasher will never beat a pro in Smash.