Goal: Win a league title with a team, starting with all letters of the alphabet. Start with A, end at Z. 

Rules: You can only have players that start with the same letter of your team. 

Examples: A for Arsenal, F for Fiorentina, a spicier version is the Macclesfield challenge where you can buy players who start with Mc or Mac.

Goal: Replicate a real world manager's career by managing his team and winning the same cups and leagues. 

Rules: You can add time as a further constraint (e.g., win the league in 3 years)

Examples:  Pep Guardiola at Man City, Martin O’Neill at Celtic, Aston Villa, Sunderland and Nottingham Forest, Jose Mourinho at Porto, Chelsea, Inter, Real Madrid or Man Utd, Brian Clough at Nottingham Forest

Goal: Get a lower league team and bring them to the top

Rules: A classic challenge! Aim for winning the league and/or champions league. 

Examples:  Wrexham, Brighton, Darlington, or any other lower division team 

Goal: Repeat a real world, historical accomplishment or bring a team back to their glorious days. 

Rules: Another classic! 

Examples:  Arsenal double, Retain the Champions League with Borussia Dortmund, Win the UEFA Cup with Ipswich, Partick Thistle, Queens Park, European cup final with Leeds

Goal: Bring the glory to a national team

Rules: Depending on the strength of the team, either qualify or win the World Cup 

Examples: Take Scotland, Ireland, or Wales to the World Cup, win the World Cup with a team besides France, Brazil, Italy, Spain, England or Germany

Goal: Be successful with a team of players that has limited nationality

Rules: Alternatively limit the nationality to a region, à la Scandinavia challenge (players from Denmark, Sweden, Norway, Finland, Iceland)

Examples: Only English players in Barcelona, only Portuguese players in Ajax, only German players in a German team (!)