You guys are putting too much stock into a few lines of text that change from game to game. If any of it were true, Machamp would be invincible in the Pokeverse, but he's a mid tier Pokemon, and low tier final evolution.
No Guard or not, Machamp needs to be close to Ocelot to hit him. Ocelot empties six in Machamp's Skull before he reaches him.
Ocelot wins.