Smash him with many flamers from chosen squads (5 flamer squads are so darned CHEAP too! 115 pts for 5 templates of roasting goodness is damn good.
the next thing to do would bring enough troops to keep the others at bay (cus once your chosen get stuck in they cant flame anything) sonic weaponry works wonders. Hell, use a doomsiren (super powered flamer of death, even kills those ymgarl gene sneakers easy!)
and finally for heavy support, oblits can be a powerful option being able to roast big bugs and little ones with ease, but for 155 points you can bring 5 men carrying FOUR missile launchers.
that means you could bring 3 sets of them for very little points, thats 12 frag, OR krak missiles at your disposal! The best part is, most of his MC's cant defend against the kraks Ap (they need the expensive 2+ armor save upgrade just to survive) and these missiles will instagib any zoanthropes he decides to bring.
if you run out of big stuff to shoot, pile on the blast templates with frag missiles!
re-cap
Flamers and frag missiles for the little ones.
krak's for the big guys (12 kraks could possibly down a tyrant on the first volly (if your lucky you would still have 4 shots left!)
sonic weaponry to pepper him to oblivion
and lots troops to keep your stuff safe.
good hunting