Just to confirm, playing 1xMC only is NOT an illegal formation. This morning I played a guy in the League that selected only 1xMC (3xAMs), I countered with only 1xMC & 2xDCMs. Possession was about 60-40 my way. When I was up 3-0 not long after half time (about 52nd min) I retreated my AMR & AML to MR & ML, & possession barely changed, finished 62-38. If playing 1xMC was illegal, then possession would have gone far more strongly to me during the second half.
So any 3 yellow players on the field would make up a legal formation.
