So Elephant Archers are pretty much useless right now. Their only advantage is being tanky, but even that isn’t true against anti-cavalry units, which leaves them a slow, weak, frail unit that costs a huge amount of resources.
But what if you could garrison other units on top of them!
Give each one a single garrison space. Then, you can garrison any archer, infantry, or monk unit on their back!
The unit on their back could not be manually controlled. It would shoot at whatever the AI directs, and monks could only heal, not actually convert. Kill the Elephant Archer and both units die.
BUT in exchange, you can get safe, protected healing, or a high-hp hand cannoneer mounted atop an elephant! Or heck, throw an elite skirmisher on there and get the tankiest genitour in the universe. Even before you account for stats, that’s awesome!
Elephant Archers on their own would still be relatively useless, but garrisoned with other things and suddenly they could provide an opportunity for powerful off-the-wall strategies!