Assuming you do have the early advantage and a better eco, you should be able to pump out a few airs/waters. It also doesn't hurt to have tower control + spawn. If they still manage to mass up shadows, the best option is to bait them, then put up a blind gate after they've stealthed, and finally, catch a few with waters. Your airs (and fires if you have them) can pick off the frozen ones.
Beware of magikills, as their electric wall can take out your airs pretty quickly. If you see a magikill, focus fire on them with all you've got.
Further, 2-3 treatures can be very beneficial for you; if you somehow lose your ranged supports, scorps & some death blossoms can make the difference.
Just make sure you have one extra water:shadow fielded before an attack and an earth somewhere (not including the one you used for blind gate), as there's always the danger they might have a last minute addition like a giant or something, then you can pull a V and deal with whatever's coming.
While you will be sacrificing 400 gold for the blind gate, if you can pick off at least 1-2 shadows, it will have been worth it.
Charrogs will be pretty useless in this situation, as 2-3 stealthed shadows will take it down quickly. And don't even bother with infernos, as shadows are just too quick to catch with them with those lovely AoE. To counter shadows, you need quantity, not quality.
Scorch is a bit risky as its more expensive and you run the risk of not actually killing any shadows.
tl;dr: Waters, single-element armies, bait, blind gate, and quantity over quality.