this thread is a joke. anyone who plays pvt would know that with well-positioned tanks protoss just melt down like cheese in microwave.
Alright, immortals can be useful against tank with the strong shield and all. but are tanks always alone? Ha! barely. They are swarmed with marines (it's a common thing to see around 3 tanks with 20-+ marines) which can kill immortal like a freakin' ant. alright, let's say you shield them with sentries, blink stalkers and non-upgraded zealots with 3 immortals, the terrans would have around 5-6 tanks by then. that's when the immortal shields start to fail. stalks blink in? no problem. stim+marau can chew up the stalkers like papershredder. oh, but if you blink in stalkers the tank will kill their own units! don't kid me. people have hands to control such a simple task. what about if the protoss go for air? what, phoenixes lift? marines can shoot them down like a sitting duck. voidrays? marines or vikings (they ought to have them if you ever changed to colossus) will kill them. chargelots? sure, they work well, but against terrans whos army is entirely based on long ranged units (except for predators, but that's in campaign.) zealots take more fire than damaging them. warp gate is stupid? don't be an idiot. it is known that it takes ages for a single zealot to warp in using a standard gateway. chrono boosts have their own limits, so don't even count them in. my point is, when pvt, terrans have the unfair advantage unless they turtle.

Smart terrans usually take over the Xel'Naga Watch Towers, if you don't know. Tanks take like 3 seconds to get to siege mode, and usually MMM ball will form a wall in front of the tank to stop any incoming hostile units. I've tried it numerous times, oh yes. Fending off early terran push from the base is a piece of cake. 2 stalkers and a sentry can do the job already lol. but the problem is mid-late game, when all your units fight outside in the open place. Phoenix harassing does not work well against terrans due to their anti air unit is a tier 1 50 minerals the cheapest long ranged unit in the game (except for infested marines, but you get the point.) High templars work well too, but most terran players run off or kill the ht first when they see it with their tanks. Usually i go blink stalk with high templars and sentries for obvious reasons, but it still doesn't work. those mass medivacs, they just don't let the petty little marines go to hell. Marauders also need to be hit with 2 storms consecutively otherwise the vacs will heal them.