IIRC, you can know the exact location of each tau base you need to destroy via the objective screen. Just click on the particular objective and the mini map will automatically highlight the location.

Wych sux ?? You really LOL me big time man, they are one of the best shocker if not the best shocker in the game. They are fast, OK hp plus the AOE stim pack ability and frankly PSM can match them, but wych come in tier2.5 WTF. I do not understand why the statement of wych sux compare to the rest factions' infantry.

SM -> They never have shocker, and their infantry tanker only come in tier3

Chaos -> PSM came in tier3. Zerkers should eat wych alive, but dont forget, Chaos is always a melee powerhouse, beating the enemy strongest point with your disadvantage, it's just suicide.

Eldar -> Banshee might be closed match up to wych, that's when they have CoW and have at least 2 squads.

Orks -> Nobz is tanker, not shocker. Basically AE unit but slow and expensive.

IG -> They never have anything when it come to the art of shocking/flanking. Orgyn ?? Slow, clumpsy, OK hp and low on number, without priest they are just pure walking rubbish can.

Necron -> Same as IG, they never use their infantry to tank.  FO ?? Oh yea, they are only good at bashing base. Against anything that know how to "walk away", they are clueless.

Tau -> Flanking/shocking is never in the teachings of Tau, they prefer to shoot their bullet right through your front door. And dont tell me kroot, eat them for breakfast every morning.

SoB -> These holy sisters only know how to burn ppl from afar, when it come to tanking, they cried to their holy emperor.

Warpbeast is decent as tanker with decent DPS, you must always get the trainer as morale is their weakness. Combine them with wych and you will have a mighty force that could quickly chew down enemy firing line, which I believe is the viable strategy against Tau.

I will forgive for one who do not know how to fight Tau.

When assaulting Tau, priority kill list goes like this,

-> Broadside - The ultimate AE, luckily they cant move when they are at their deadliest moment.

-> FW - FW is slow, so the point here is dont let them stand and load, make em run.

-> Tau Commander - With every gear he and he will become a AE *******, send your archon to cc him.

-> Kroots and other dinosaurs alike -> Kill em last because they are meant to eat up the bullets for Tau firing line. Ignore them until you take down their fw line.
So for DE vs Tau, send in 1 squad wych + 2 squad beasts, stimpack them and let beast take down the broadside first while wych + haemo go chase fw, and dont attach your haemo to any squad FFS. Made him range stance and use his first ability near the fw so they run slower. If TC is there, archon go find TC, if TC is not there, go chase fw also. And make sure you use archon lock down ability on the fw. Rekindle archon and you can lock down 2 fw at one go. Why you need seer council for ?? SC sux to the max and ex like hell.

And behind your shockers make sure 3 fully upgraded scourge is there. If barracuda is there, concentrate scourge fire on it first. Once those barra down, jump over to fw and kill them off. If Tau got kroot or dogs or dinosaur, throw in 2 Talons to play with them until the tau firing line is gone.