I took my treeman up with my general (mounted armed with hail of
doom arrow) escorted by 5 dryads.  I kept the tree man ahead so he'd take
any charge.  The round before the enemy charged I used my general to unleash
the hail of doom.  Just so happens I was up against about 20 or so boar
boyz.  I scored 15 arrows on the 3D6 roll and whipped out about 7-8 of the
boar boyz.  I also had wheeled the dryads so that they could flank the
stupid orks.  Of course the orks charged my treeman.  Soon to be flanked by
5 dryads and my general in his unit of skirmishing glade riders.  I toasted
the entire unit without a single loss.  I guess what Im saying is that i've
found that taking on core units is pretty simple.  Just throw your treeman
upfront to take the charge, then have a few of your cool troops behind to
help out the big guy.  Charging Warhawks from behind would be exellent for
this.  Wardancers as well.  But being these boar boys were pretty tough, I
chose harder hitting troops to take the blunt of the orks