Guard mode for 1. Try to have your units stopped before they are hit.

Unit sizes is a big factor here, if on huge unit sizes go for about 10 deep. Also put your cohorts/hastati/princepes on fire at will to disrupt the chariots charge.

Have a few reserves and when the chariots hit, rush the reserves to the hot spot and they'll fal like flies.

But my favorite is wardogs nothing like making them duke it out over a cheap unit