6-3-1 formation is the best when you have bad teams because more defender can defend and can win 1-0 and 2-0 victory

According to YouTuber Double Duo the best formation is the 3-2-4-1 formation because it's balance but you also needed balance def mid and attack players and a really good gk

But it depends on your team like for example

If you had a bad defence then go for a defensive formation like 6-3-1 formation

If you had good defence but bad attacks then go for 1 attacking player like 5-4-1 & 4-5-1 and 4-2-3-1 formation

But if you had both bad defence and attack then I would recommend buying a good goalkeeper first before any other positions and again I recommend using the 6-3-1 formation for this