
Managing a club in Football Manager where you can only sign players from a specific region or country means you have work to develop your youth players, make do with and improve the players you have already got and scout distinct players well.
So here are the top 5 clubs that are more difficult to manage than your average team in Football Manager, but so much more rewarding.
Athletic Bilbao (Spain)

Most football fans will already know Athletic Bilbao's Basque only transfer policy which allows them to only sign players from the Basque region of Northern Spain and Southern France. Despite being one of Spain's most successful clubs, Athletic have not won a major trophy since 1984. Your challenge to top Barcelona and Real Madrid will be difficult but at least there is the famous youth system and the excellent training facilities to help you on your way.
Athletic have a strong squad which can compete for a European place from the start including key players like Iker Muniain, Iñaki Williams, Inigo Martinez, and Yuri. Also, there are talented youth players coming through the system. But, it is worth taking note, that paying considerable attention to the youth teams is extremely important as player recruitment is so much more difficult.
Depending upon how strict you wish to be in-game, it is possible to sign Spanish players aged 16 and they will naturalise as Basque. Or you can play as Bilbao without this option making the save tougher. Scouting players from Real Sociedad, Alaves, Eibar, and Atletico Pamplona (Osasuna) is also key as they will provide you with the main source of signings.
Chivas (Mexico)

Club Deportivo de Guadalajara or Chivas are one of Mexico’s most successful sides. They restrict themselves to only signing Mexican nationals. Chivas have one of the better squads in Liga MX with experience up front in Mexican international Oribe Peralta and dynamism in midfield through Dieter Villalpando.
The Chivas youth system is one of the most famed in Latin America with players like Javier Hernandez, Carlos Vela, Carlos Salcido as well as former Football Manager wonderkids Carlos Fierro and Erick Torres having come through the system. The club’s youth recruitment is the best in the country
One key to success is keeping hold of Jose Juan Macias. The 19-year-old is a talented poacher who can also play on the left-wing.
Turning Chivas into the dominant team in North America and then the world will be a fascinating challenge.
Altinordu (Turkey)

Turkish second division team Altinordu are an interesting challenge. The club historically has had the restriction in which only domestic players aged between 18 and 25 can play for the club. This means that you'll be forced to use and develop the club's youth system in order to create a talented young first team. Altinordu has based their development system on the idea that a good player and a good person makes a great citizen.
Altinordu already have excellent training and youth facilities so this should help you in your push for promotion to the Super League and to eventually take on the might of Galatasaray, Besiktas, and Fenerbahce. Your objective should be to try to become only the sixth Turkish team to win the league title.
Indian Arrows (India)

In a league where all opposition teams can have up to 5 foreign players in the playing eleven, Indian Arrows can all only have Indian players. Additionally, the standard of Indian players in the league is a lot worse than the foreigners who are there. This means you are in for a serious challenge trying to compete with your rivals. The team is comparatively very weak. So, as you might expect, the Arrows are expected to finish bottom of the league. At least, at the start of FM20, Indian Arrows' oldest player is only 20 years old so there is plenty of youth to develop in the team.
Niigata Unicorn (Singapore)

The final team on the list has a unique rule which makes it even more different to the other clubs on this list. Niigata Unicorn may only sign Japanese players despite the fact that they play in Singapore. The reason for this is because Niigata Unicorn is an affiliate to a Japanese second division club of the name. Niigata joined the then S. League in 2004 and have since become one of the most successful teams in Singaporean football, including winning the league title three times consecutively, due to the Japanese investment in the club.