My colleague (bronze league) asked me a moment ago what he should have done as protoss against the marines and marauders supported by tanks that attacked him yesterday.
I recommended sentries to reduce the marine damage, zealots to hurt the marines (with speed upgrade if possible) and 2-3 phoenixes to lift the tanks up so your zealots actually reach the enemy. Then blink in with stalkers to kill the (remaining) tanks as quickly as possible while the zealots divert the marauder fire.
It seems to be an overly complex solution that requires good micro he might not have, but was the first solution that came to my mind. What would you recommend?
A solution for all races would be good since others playing other races might find this question.
Best Answer
For protoss you have to make excellent use of Sentries to delay your enemy. If possible, try to split his army in two with Force Field(s) and take on that half by itself with your zealots, sentries, and stalkers. You won't be able to take him in a head-on fight as Marines/Marauders dominate your T1 units.
Use this delaying tactic to get a few Immortals as soon as possible and transition into Colossus with the range upgrade. The splash damage is very effective against the tightly clumped Bio Ball, while Immortals can take many hits from Siege Tanks. Use Blink Stalkers to get close to the tanks and focus them down. Note that once you have a few Colossi, your opponent will usually get a few vikings to counter them, but focus them down quickly with your stalkers.
Honestly, it is a very difficult thing to beat as Protoss if your opponent is of better or equal skill, especially since you have to tech to very expensive units just to counter his (mostly) T1 army. You'll just have to delay and outplay them and not make any mistakes, and make sure you are very proficient with your Force Field and Guardian Shield usage.
Another option is to go High Templars with Psionic Storm and Feedback on the Medivacs, but I rarely go this route as it is too gas-intensive and higher level Terran players will just use Ghosts which nullify High Templars with their EMP ability (Removes all energy and 100 shield points). Not to mention if your clump of High Templars goes within range of a Siege Tank you're dead meat.