I'm not sure what 2 fortest formations means?

If you're looking for a counter to the narrow diamond, the 3n-5-2V/3n-1-4-2 are probably the strongest counters. 4-5-1V/4-1-4-1 are decent choices too. I'd be a little weary with the 4-4-1-1 and 4-3w-2n-1 against it since neither is real strong defensively in the central midfield, and the diamond user will be focusing all his efforts there.