In MP elephants are not that useful when the opponent expects them, as many said.
Yet if you have either Berserk, "Ironed", Ethereal and/or Flying (lol) Elephants (through spells Berserkers, Iron Warriors, Body Ethereal and Flight), they're rather fun and more difficult to counter/kill
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Behemoths are a nice variant, they're rather "better" tramplers because they don't rout, but have very low MR and are banishable (undead).