Well for elephants you'll want to focus on getting those riders down first, makes everything way easier. Huang gai's bomb charge works perfectly for this and its pretty satisfying watching them tumble off. If you're playing someone like sima shi, his c3-ex attack absolutely destroys mounted commanders, and you get nice time bonuses for each one.

The nice thing about elephant units is they're super slow and cant squeeze through tight spots, so use that to your advantage. You can basically dance around them with faster characters and chip away with hit and run moves. Archers like huang zhong are really good at this since they can safely blast away from distance.

Something interesting - fire attacks work great for weakening their defense, and ice effects slow them down even more. If you're in nanman stages, might want to save your allied officers first before going elephant hunting since those things love breaking into camps. And hey if you manage to capture one yourself they're actually pretty good at smashing through castle walls which is always fun.

Just remember to watch your positioning and take advantage of the terrain, mountains and narrow paths are your friends here. Once you get the timing down on dodging their charges its not too bad especially if youve got a quick weapon equipped.