General PvP Strategy
From Liquipedia Starcraft 2 Wiki
PvP (Protoss versus Protoss) play is highly dependent on a player's initial build order, scouting, and tech choices in comparison to the other player, because both players are building along the same tech tree. This means that one player's tech choices must either be surmounted or completely subverted through the use of another (or the same) branch of the tech tree than (as) the opposing player. In general, Robo > Twilight Council > Stargate > Robo. However, it is by no means a build order win.
For example, if a player were to attempt to do a 4-Gate rush on another player, the other player would have to either 4-Gate faster than his opponent, or counter it with the proper tech.
A common thought running through most players not opting for an aggressive Gateway-oriented build is to place Gateway units including Sentries near the ramp in order to Force Field to prevent the opponent from invading the base. Fights on the ramp with good force fields cause the opponent's numbers to count for little, as the defending player force fields small numbers of units up the ramp where they may be picked off. Minimizing Sentry count is an important facet of PvP as they lose effectiveness later in the game, but cost 100 gas.
 Common PvP Build Orders
- Gateway units are essential throughout the game in PvP, and are sometimes very effective against certain high-tier units. The exceptions are the Colossus, which is highly effective against all Gateway units, and the Archon.
- Zealots are extremely effective meat shields for a PvP army due to their relatively high HP and low cost compared to other units. They also have decent DPS that can be improved by Charge.
- Stalkers can kite Zealots indefinitely so long as the Zealots do not have charge. However, mass Stalkers are directly countered by Immortals. Zealots are effective against Immortals.
- Sentries are extremely effective for defensive purposes early on, but lose their effectiveness as the game continues. Therefore, defensive builds try to minimize Sentry use.
- Phoenixes can be used to disable Immortals and other Protoss ground units, as well as to attack Colossi. Phoenix harass on workers however can be deterred by a single Photon Cannon protecting the mineral line.
- Immortals fare extremely well against Stalkers and deal massive damage against Colossi if they can get in range. With their Hardened Shield, an Immortal can tank up to 26 Stalker hits and 12 Colossi attacks.
- Colossi are often the defining unit in a PvP match. They are fragile however and must be protected from units that can take advantage of their slow movement speed and vulnerability to air attack. A single Colossus has 350 hp and will require about 25 shots from a Stalker to kill it.
- Phoenix can be a hard counter to mass Collossi with appropriate Gateway units to prevent attack from the ground. Stalkers will bring these units down, although good positioning can win you a battle due to their fast movement speed and ability to use graviton beam on problematic units.
- Void Rays can be effective when a player is overly investing into Colossus production, but are otherwise quite uncommon due to their weakness against Stalkers and Phoenixes.
- High Templar are rarely used in this match-up given that Feedback can only be used on two common Protoss units (Sentry/High Templar) and the Mothership. Psionic Storm also has limited effectiveness except against mineral lines and maybe air units.
- Dark Templar have a lot of potential early in this match-up and even throughout the game. Players often neglect to acquire detection early on in the form of Photon Cannons, and Observers are sometimes skipped in favor of an early Immortal, or any that have been made are out scouting. Well placed Photon Cannons can limit or even spoil their effectiveness, but lone ones can be destroyed as well. Having Dark Templars in one's main army can also be effective if the enemy player does not often bring an observer with his forces.
- Archons make short work of all Gateway units (with the exception of the Stalker) due to their bonus damage against Biological units [not to mention the splash damage as well], naturally spread out your forces due to their size (which is useful when fighting against the Colossi's lasers), are able to tank damage, regenerate whilst retreating, and can still put a dent into any non-Biological unit. On the downside, though, the Archon is difficult to micro because its attack is slow and it is unable to move for a time after the attack's damage has been dealt.
- +1 Weapons upgrade will allow a Zealot to kill a Stalker and Zealot with one less hit and a Stalker to kill a Zealot with 1 less hit. Immortals with this upgrade will be able to 3-shot Stalkers instead of 4 shots.
- +1 Armor upgrade will allow a Zealot to sustain 1 more attack from a Stalker and 1 more attack from a Zealot. Same applies to the Stalker.