I've been thinking I'd like to have this option: ML with no transfers at the start, so you get to do the first half of the season with more realism, with real world line-ups.
Of course, alternatives are to just ignore the first transfer season, but the problem is your team won't change but the others still will... Or to play League mode but then you have no Team Spirit and no transfers ever...
Is there a way you can think of to stop ALL teams from transferring players in the first month of ML?
Yes there is but it takes effort, time and some patience. The transfer market is actually pretty smart. AI transfers fill gaps in the team based on the current "game plan" setup. I managed to stop all transfers or 99% of them while a AC Milan in Serie A (basically no one over 70 is transferred in or out in the first transfer window). Here are the steps:
1- Start a ML and simulate until the end of the transfer window.
2- Take note of the transfers that have happened in the transfer window (note the AI transfer actions will not vary much from one save to another since the game plan and ratings of players change very rarely in the first month of the simulation). Decide which transfers you don't want to happen. Write them down (player, buyer, seller, position and rating). Exit ML and enter edit mode.
3- I'll go through an example, but I'd be happy to discuss any specific questions/solutions for special cases.
Let's say Genoa plays 343. The RM position in real life is filled by Ansaldi, but Ansaldi is registered as RB or LB. The AI will then think to buy a player with a registered position of RM to fill the gap and sell RB/LB players since they are not part of the game plan. You can prevent such transfers either by adjusting the game plan (at least the default formation not necessarily offensive/defensive) to match the pool of players they have at day 1. OR you can adjust Ansaldi's registered position to RM. Restart a new ML and Genoa will not buy a RM or sell Ansaldi (or will buy a reserve one less than 65 in rating who will never really play).
4- The AI transfer is "buying" based. Also, teams do not upgrade (e.g., sell a 75 rated winger and buy an 80 rated one). If no team needs an RB, then no RB transfers will take place. So fill gaps with unknown young players.
5- Finally, filling the team's rosters in edit mode to maximum size with young unknown players limits the likelihood of transfers in all of year 1 including January window. Transfers start again in season 2 at regular pace since contracts expire.
Hope this helps.