if both people do it its not much of an advantage, other than indias need for only food kinda makes it easier to manage, but you would certainly have to if you want to keep up with someone who did. its then an all out brawl and quick game. Some civs its just not good to do with, like Russia, Azzy, Lakota, Japan, Dutch, france etc… but other civs can get away with it… Brits, ports, spain, india, Otto (is great because vils come back for free) germans
4 extra mahouts is no joke, a couple mahouts isnt that big a threat if dealt with, but if you start getting 6-7 mahouts backed by lots of inf, it becomes a lot to handle. You may snipe a couple down, but then have no way to deal with the mass of the rest of them.
A faster train time for Camels is what is recommended to help mitigate the slow train of all their best units. But though its the slowest training, its also the fastest building civ too, so makes it very hard to actually destroy FB unless you have port or japan mortars. When playing on maps like G plains and mahouts train instantly it is very OP, and bennefits India more than other civs, I do not think mahouts need faster train times. (better pathing YES) also to note, flail eles are better use of pop space and resources at the moment from my understanding, try making just mas flails.
japan is very strong civ no doubt.
Gends and spahi also have devastating attacks. and sowars are cheaper so should be weaker units.
if people are behind walls, use elephants, and siege eles to break them down. If you have pushed people behind the walls you are winning and in control, so you do not need to press in hap hazardly, but work away slowly at it… a hint is to target the post in the walls and use units spread out along the wall to spread the damage and get very large holes made that do not cause choke points. its a lot of hypothetical but yes walls ruin the chance of CAVALRY (mahouts or what ever) from doing their job. It breaks the normal stratedgy of how you fight when there are no walls. open field india has one of the best melee games.