I just got 0 losses on the last part pretty easily, almost no micro required. Here's how:
Top: Send your stalkers and archons. Have them attack the battle-cruiser immediately, then once it's dead just attack-move to kill the rest. No micro required.
Middle: Send the sentry and your collossi. Put all three collossi above the cliff (tell them to hold-position), and create a collosus-hallucination below it (run the sentry away so he doesn't die). When the hallucination dies, bring one of the collosi down to draw their fire away from the pylon. When it's nearly dead, bring it back up the cliff and bring another down. Before the third one dies, all the enemies should be dead. Very little, very simple micro.
Bottom: Bring your immortals, phoenixes, and high templar. Use the templar's storm on the marauders immediately (run him away so he doesn't die), then attack-move the immortals to the back so they kill the marauders then the tanks. Meanwhile, use all your phoenixes to graviton-beam some siege-tanks near the back. You'll only need a little micro to move some low-health immortals away (I only had to move one).
It's all a matter of using the right units :) Note that I did not use the zealots at all - they died too easily.