You are Not Alone
The main difference between 1v1 and team games is that you have one or more people to rely on to cover the weaknesses in your overall strategy. While this may seem completely obvious at first glance, in my experience, a lot of people used only to playing 1v1 completely miss this very simple fact.
Terran Up the Night
Consider the Terran race. Its units are divided into three categories:
- Infantry, a.k.a. Bio
- Ground Vehicle, a.k.a. Mech
- Air Vehicles, a.k.a. Sky
As the time of this writing, the main strategy in 1v1 is Bio with a dash of Mech and Sky. Mech alone isn't viable because of its lack of mobility in a meta that favors game-ending harassment, while pure Sky Terran isn't usually done because it's too gas heavy (you need at least some Bio to serve as mineral sinks and for ground support).
Furthermore, each unit category has their own separate tech and ugprades. Below are the core upgrades for each category:
- Bio (5) - Engineering Bay (Attack, Armor), Tech Lab (Stim Packs, Combat Shields, Concussive Shells)
- Mech (4) - Armory (Attack, Armor*), Tech Lab (Infernal Pre-Igniter, Drilling Claws)
- Sky (5) - Armory (Attack, Armor*), Tech Lab (Cloaking Field, Hyperflight Rotors, Advanced Ballistics)
*Mech and Sky Armor Upgrades are shared.
In 1v1, when you finish Infantry Weapons +1, all of your Marines, Marauders, Ghosts, etc. are upgraded to 1-0. If you have a large infantry army, this gets you a lot of mileage for the low price of 100 minerals and 100 gas. The same applies to Ground Weapons +1 and Air Weapons +1 for their respective unit categories.
Department of Redundancy Department
However, in team games, your upgrades do not apply to your allies' units, even if you're the same race. When Aron gets 1-1 on his Marines, Moses's infantry stay at 0-0. Likewise, when Moses gets 1-1 on his Mech army, Aron's Mech units stay at 0-0. The same applies to tech and special abilities. If both Aron and Moses went for Bio play, they'd both have to get the same upgrades at the Engineering Bay and Tech Lab:
- Infantry Weapons (100 minerals, 100 gas)
- Infantry Armor (100 minerals, 100 gas)
- Stim Packs (100 minerals, 100 gas)
- Concussive Shells (50 minerals, 50 gas)
- Combat Shields (100 minerals, 100 gas)
Total Cost:
Instead, what Moses and Aron should've done is to specialize in order to avoid redundant upgrade and tech costs. Moses decides to go Bio and spends the abovementioned 450 minerals and 450 gas. Aron decides to not spend any money on Bio tech and upgrades and goes for pure Mech. He doesn't get anything but basic Marines early on (so they don't instantly die to rushes), but then quickly transitions into pure Mech. In this second scenario, the team of Moses and Aron suddenly have an extra 450 minerals and 450 gas to spend because they didn't waste it on redundant tech and upgrades.
Division of Labor
The key to success in team games in Starcraft 2 or in any other team game (or real-life collaborative effort) is division of labor. One player goes Roach/Ravager, while the other goes mass Mutalisks. One player builds an early ground force while one or more players techs up to try and get powerful air units. On their own, such strategies would be countered easily by a competent player in 1v1, but together, they can cover for their own weaknesses.
Division of Labor becomes much, much more important the larger the game gets. Picture a 4v4 team of four Terrans who all decide to go Bio. Now, instead of one player spending 450 minerals and 450 gas, the entire team collectively spent that four times (wasting 1350 minerals and 1350 gas on redundant tech). While they would have four times the amount of Bio as having one player go Bio, that army is a one-trick pony that can be hard countered by a smart enemy team. One enemy player going Siege Tanks can hold them off with the help of his or her team, and suddenly Aron and Moses and their two stupid buddies are raging at each other in team chat.
To sum it up, when playing team games, pick a highly-specialized strategy that doesn't overlap with your allies, and stick to it. Rely on them to cover your weaknesses, as they rely on you to cover theirs.