As a manager I use a strange formation, with hard attacking from the side my oponent has some weakness.

So my strategy is to have always more goals than my oponent and that worked fine so far in League, CL, Cup.

Even in the cup that I am the weakest in level of all teams I managed to win all games home and away with the same formation and orders. Often facing the 4-4-2 formation with big success.

I play a 2-3-2-2-1 like this :
-ST-
-AML- -AMR-
-MC- -MC-
-DML- -DMC- -DMR-
-DC- -DC-
-GK-

The AML-AMR-ST-DMC have to be at least 5 stars otherwise there is no use to play an attacking type of game. The DMC is highly important as most of the attacking attempts of the oponent stop there. So I focused on a 5 star (became 6 star few days ago) DMC and improved his Physical&Mental skills to have the best fitness and mainly speed. I see loads of players focusing on attack and defense in the distribution of skill points but P&M factor is highly important to break a counter-attack if we choose to play attacking and stay open at the defense after a failed attack.

What I have to say about formation is that it's not the most important thing to counter another formation if not used wisely with correct orders.
If you choose a formation that your players haven't played before their performance will fall.
There are other factors to block a good team, like what type of player u will use against who and where, the orders you will give to your team, etc...

Note that a player with 1 star less can perform much better to a 7-8 form that a stronger player that has a 6 form.
After loads of studying and experimenting I managed to have 7-8 and 9 in each game from all players.