Have there been any additional changes to the composition for fantasy? At last read, I believe they were as follows:
1125 points per player - no sharing
0-2 characters and 1+ core choices per player, one player may take a lord vice hero choice
Team must have 3+ core, <=4 special and <=2 rare with no other restrictions so one player could bring 1 core, 4 special, 2 rare and zero characters if they wanted.
If consideration is still being given to the composition rules, I would suggest the following ideas for consideration:
1. no lord choices - a single greater daemon or tooled up lord character can chew through just about anything. Eliminating lord choices would field more units and make for more "thinking" battles.
2. different armies - a team must have different armies to avoid simply taking a 2250 point list split between two people.
3. 0-2 characters but otherwise each player must have a legal list (i.e. 2+ core, 0-3 special and 0-1 rare).
Just some food for thought.