The typical Gundam is at least four times the size of a standard Knightmare Frame and possesses weapons and durability far in excess of even the most advanced KMFs. Even a grunt unit like a Zaku II, GM, Leo, GINN, Windam, Flag, or Tieren would be more than a match for any Knightmare Frame. Only advantage I can see for the Knightmares is their small size, which makes them harder to target and allows them to hide in places where the Gundams can't get to them; even so, they'll still get pasted with a single shot, and the majority of Knightmare Frame weapons won't do more than scratch the paint on the Gundams.
By the way, Gundam Heavyarms would be a far more appropriate matchup against the Mordred, seeing as they're both heavy artillery mecha. Sandrock versus Galahad would be rather unfair, seeing as Sandrock possesses ranged weaponry (even if it's just two head-mounted Gatling guns in the Kai variant); Epyon would be a far more appropriate foe, as it and Galahad are both melee-only.
Of course, if all you want is a curbstomp, just bring out the RX-93, the F91, the Strike Freedom, and the 00 Raiser and call it a day. Not even Suzaku's "live on" command will allow him to weasel his way out of the asskicking he'll receive.
