A hoplite/phalanx front line (recruitable or mercenary) with javelins behind will quickly and effectively dispatch any elephant army with minimal casualties. If you want, have some archers with fire arrows behind the javelins but these are not essential. Fire arrows will cause elephants to rout only if elephants are at least winded. Using archer only armies is reckless and relies more on luck than anything else. If nothing else is available militia hoplites are sufficient to rout elephants with minimal losses but never allow the elephants to hit you from the side or rear as the consequences are terminal. Preferably you want to make them run amok so that they wander into their own lines causing further devastation.
This hoplite/phalanx/javelin formation is also extremely effective against chariots.