Here is the insight that I have to offer. They have no big blocks really, mainly skirmishers.
You won't face Eternal Guard (WE spearmen essentially) unless the general is playing a fluff based army. The choppiest stuff you will face are Treekin and Treemen. The rest, wardancers, dryards, etc, witll break apart on a frontal battle against Saurus spears.
The WE player has a few choices. Usually it's 1-2 units of bowmen, deadly accurate, but VERY soft (T3, no armor), usually not skirmishing. 1-2 units of dryads, but an EoTG will tear them up. You get ST5 on the bomb vs forest spirits and they lose their ward save because the attack is magical.
So, EoTG is one of your best friends in this case. So is a Slann with fire magic. With his Fire magic you get X2 wounds on the Treeman and Treekin who are flammable, and you negate their ward save as well. Brutal stuff.
The four biggest threats you will face are:
The Alter: A lone WE hero who fires the Hail of Doom arrow. One use only, 3D6 S4 hits, usually on a 3+. Can effectively wipe out a unit of their choosing. But again, your EoTG ward save is the best resistance. If he was smart he would hit your Cold One Cav with this and try to remove them early, but who knows. The more targets you can present him, the less likely his to choose what you don't want him to shoot.
The Surfling Treeman: Most WE generals put their Treeman and a Spellsinger in a wood and surf it up to your line to keep the Treeman from being killed, then stepping out to battle or using his Strangleroots to take out small units and lone foes. Again, the EoTG bomb can clean that out, but if you can keep some Terradons in the wood, on the edge, then he can't surf, and you can flee when he charges you, driving him into the open. JUST PASS THAT TERROR CHECK!
Wild Rider Flank: Most generals usually run a flank of Wild Riders to try roll up your flank. Stop them and redirect them with small units of skinks. They are also super vulnerable to shooting. So focus shots on them for the biggest points trade off. Terradon rocks can also be brutal here.
Sneaky Bastard: Watch any unit of tree-spirits wholly within a wood with a hero. There is an item, the Moonstone of Hidden Ways, that allows him to teleport that unit to another wood on the board once in the game. So, depending on terrain, you can be staring at Wardancers, Dryads, Wild Riders, and if he is especially sneaky, Treekin, sitting on your flank or rear in the 1st turn. Keep crap in the woods, skinks and what not, to prevent him from teleporting, as he needs an empty clear wood to do so. Other than that, stay as far away from woods as possible.
In general, magical and flaming attacks are your best friend. The WE have few things that can take a Slann/TG block head on without a supporting flank. Castle up your center, redirect his flanks, and magic the sh*t out of him.
Thats the best I can offer from playing several games as WE's myself.