There are lots of good recent threads on this already, just scan the forum:
viewtopic.php?f=5&t=27265viewtopic.php?f=5&t=27117viewtopic.php?f=5&t=26534viewtopic.php?f=5&t=24930You didn't say which type of elves, but there's a link up there for high elves, Galadhrim, and wood elves.
Basically, you can't take anyone head on*, you have to use terrain**, hold positions by shielding so that more numbers can be brought to bear elsewhere, and direct all shooting to spear and pike support.
*That said, if you have Rumil backed by pikes, flanked by a pike line on each side (but not too close), that formation will slaughter just about anything it touches.
**Are you using enough terrain? The game suggests 33-50% board coverage, but I've seen a lot of people play on an open board. Use terrain to break up enemy formations and hold gaps.