There is no doubt for me that 442 has the best pitch coverage of all formations. Therefore it doesnt have any obvious weaknesses. The point some poster said there's so many counters for 442, kinda proves my point. The best counter will be the formation your team plays best IMO.

Having said that, the only formation that would make me change my 442 is another weaker 442. For some reason the game benefits the weaker side in these situations. So, if you're weaker, then perhaps 442 is your best counter vs 442.