I’m looking at the Event Assembler language.txt, and it says:
Leader char = Leader character of this unit. Leader character is usually either main lord or enemy boss.
But, does it affect in some way to the units?
If not, it’s possible to create a leadership system like in FE5, where some bosses give bonuses to the units, with that byte?
I know the leader byte is used for AI1 0x0D and turn order.
AI1 0x0D = attack only if leader has a target in range (should be paired with AI2 0x03 and a nearby leader with [0x00,0x03]). AI changes to [0x00,0x00] after the leader dies. (Also, units with AI1 0x0D need to be set to auto-leveled in order for the leader byte to be read)
By using this AI you can make a group of enemies that can’t be lured away individually. You typically want the leader to be the unit that is farthest back in order to force the player to be exposed to multiple attacks. It’s such a shame this AI went virtually unused in GBA FE.
The leader byte also affects general turn order:
Wounded units in recovery mode
Units without a leader (typically the boss)
Units with a leader
So, assigning a leader to the generic enemies will cause the leader/boss to act sooner during the enemy phase.