All players have one thing in common (Challenge)

[Speedyol]

Want a new interesting save, with a odd limitation to make it harder or more challanging to find good players? 

-How easy/hard do you think these would be to use in the game?
-Do you have any suggestions for other conditions/features that player can have in common?

1. All player has one thing in common.
2. You cant sign contracts to players that lack this feature. Includes Loans/Trials, and perhaps also Staff.
3. You cannot renew contracts to players who doesnt have / lost this feature.

Suggestions - Every player is:
-left footed
-Weighs more than 85kg
-Shorter than 170cm (Height)
-Born on the same date, day/month (not same year).
-Born in the same city (Ex: London).
-Has Last Name starting with "pick a letter". (Ex: every last name starts with G)
-Has less than 5 in "pick a atribute". (Ex: Everyone has 5 or less in Teamwork)
-Has at some point played for "pick a club". (not your club)
-Is natural at the same position (Ex: everyone is natural at DL)