[thejeff]

Mythical creatures, that aren't part of a nation of their own, are usually found as summons, not independents. Sometimes as events.

There are a handful of non-human independents, Lizardmen and monkeys are probably the most common. And of course the various aquatics.

Trolls can be summoned. I think there's a troll attack event as well. There are gnomes, but they're only recruitable from a magic site.

The easiest way to take down Elephants is magic. They've got low mr, so single target mr-negates spells work well on them. Soul slay/Paralyze/Rage, plenty of others depending on what paths and research you've got available.

The most elegant way is fear, if you can pull it off. They've got decent morale, but if you can hit them with enough fear causing spells, they'll rout and trample anyone behind them.

Counter-elephant aren't all that good, since without trample they don't do a lot of damage. If you've got a size 6 pretender or access to other size 6 creatures, the elephants won't stand much chance. Hydras eat elephants for breakfast, for example.

Otherwise, use lots of low resource high damage troops. Defense helps more than armor against trampling, so don't bother with heavies. Even barbarians work fairly well in quantity. Remember elephants cost 100 gold, so if you lose ten 10 gold troops for each elephant you're coming out even. Aim to have twice that many and see how it goes. Spells that stop them for a turn will help: Earth Grip, Tangle Vines, Bonds of Fire are all available very early.