Below are the ones I have settled on, some have been gleaned from Trebians Wargaming For Grownups blog, well worth a read for ideas.
A command base may join a unit at the beginning of a turn if it is not engaged in hand-to hand combat.
A unit with a command base attached may once per turn do one of the following options which must be declared prior to the combat
1. Re-roll its combat dice that miss (Poor commanders must re-roll all the dice)
2. Re-roll failed combat saves (Poor commanders must re-roll all the dice)
3. Re-roll a failed morale test (Not available to poor commanders)
Joining a unit puts the command base at risk
If a unit loses a base from shooting, it must make a saving roll of 2+
If a unit loses a base in hand-to-hand combat, it must make a saving roll of 3+
If an overall command base is lost or with a unit that is destroyed, all units in the army must take a morale test.
If a subordinate command base is lost or with a unit that is destroyed, all units under its command must take a morale test.
If an unattached commander is contacted it will fight with one D6 has heavy infantry or cavalry with a saving roll of 3+.
A commander attached to a unit that is destroyed is also removed either captured or killed.
The target unit must be within a 45degree arc of the charging unit's front and in its line of sight at the start of the move to be charged.
Contacting the flank or rear is only possible if the entire charging unit is past an imaginary line drawn along the target units flank or rear.
Contact can only be made by one attacking unit per facing: front, rear or either flank.
If a unit is reduced to one base it must take a morale test every turn if in hand-to-hand combat.
If a unit loses more casualties than its opponent in hand-to-hand combat and has less bases than its opponent it is pushed back 2" any intervening friends will be pushed back with it, if unable to fall back due to impassable terrain or the table edge they are destroyed.
They will also become wavering and have a suitable marker placed next to them, should they be pushed back in the consecutive turn of hand-to-hand combat they will be deemed destroyed. If they are not pushed back again the marker is removed.
Add one dice in hand-to-hand combat it will also add one to morale test score for losing a base in close combat until a base is lost.
The escort consists of two bases. If an elephant unit charges, the escorts throw their javelins prior to the combat, they do not add to the close combat. They also give the elephant more resilience so it will rampage after six hits rather than four. The unit will also count as two units for determining losses and the army total.
Units may interpenetrate providing they can clear the unit they are attempting to pass through, the passed through unit may not move however.
Only available for unattached commanders, light cavalry and infantry, the charging unit must be at least six inches away to do this, the evading unit will end its move with its back to the enemy.
One base may fire bows at the end of movement each turn.
Troops so equipped may re-roll any dice that miss in the first hand-to-hand combat of the game.
Hun Light Cavalry
These had light spears as well as bows, they may re-roll any dice that miss in the first hand-to-hand combat of the game.
Byzantine Kataphraktoi and Hippo-Toxoti
These may fire their bows after moving.Thoughts on Republican Roman Maniples