The five Advance Wars countries are all unique in their own ways, and are probably based off of real world nations from World War II. Here is information about all five powers.
Orange Star
Color: Red
Training Missions: Controlled
Campaign Mode: Controlled
War Room Mode: Controlled
Versus Mode: 1st Army
Resemblance To: United States of America
Headquarters: American skyscraper
Orange Star CO Leader: Nell
Available Commanding Officers: Andy, Hachi, Max, Nell, Sami
Brief Bio: Early in history, the Orange Star forces clashed with Blue Moon rebel forces which seized the eastern end of Orange Star, with forces commanded by poor commanders. The arrival of Commander Olaf to Blue Moon, along with Grit's support, surprised Orange Star. Blue Moon forces were now commanded by a former Orange Star commander, Olaf from Macro Land. Eventually, Olaf's forces entered Orange Star, and Orange Star, led by Nell, drove them out. Weeks later, Olaf invaded again, this time with a full fledged force, except for the defenders on the Green Earth border. Blue Moon forces swept to the capital, but the entrance of you, the advisor, in Advance Wars 1, along with Andy, forced Olaf and Grit's forces reeling back into Blue Moon. On Olaf's tail, Orange Star forces swept into Yellow Comet and Green Earth, eventually figuring out that Black Hole was their real enemy.
Orange Star is also known as Red Star in the Japanese version. Red Star was renamed Orange Star when the Advance Wars series came to Nintendo to avoid American negativity from associating red with Communism.
Blue Moon
Color: Blue
Training Missions: Enemy
Campaign Mode: 1st Enemy (Controlled in final mission)
War Room Mode: Main Enemy
Versus Mode: 2nd Army
Resemblance: Russia
Headquarters: Russian palace
Blue Moon CO Leader: Olaf
Available Commanding Officers: Grit, Olaf
Brief Bio: Blue Moon separatist forces managed to achieve a great victory over the Orange Star forces after Olaf and Grit joined their ranks. Olaf's forces invaded Orange Star the first time with minor forces but failed to break Nell. They tried again with their entire forces, but Andy stopped them, along with the Advance Wars 1 advisor. Olaf's forces were forced to flee through Yellow Comet and Green Earth after Orange Star was on its tail, betrayed by Sturm's promised support for Blue Moon. After learning of this betrayal, Olaf joins the Allied forces invading Sturm's homeland, defeating him in the Cosmo Land War. In Advance Wars 2, Sturm is back. He sends Lash to seize Blue Moon from Olaf. You, controlling the Blue Moon forces, must liberate your country and launch an invasion of Black Hole's main island.
Green Earth
Color: Green
Training Missions: Nonexistent
Campaign Mode: 2nd Enemy (Controlled in final mission)
War Room Mode: 2nd Enemy
Versus Mode: 3rd Army
Resemblance: Germany
Headquarters: German Castle
Green Earth CO Leader: Eagle
Available Commanding Officers: Drake, Eagle
Brief Bio: Green Earth forces existed farther back than the Blue Moon forces, but their major wars did not begin until Black Hole forces, commanded by a Clone Andy, attacked Green Earth. Believing it was Andy of Orange Star, Eagle launched blitzkrieg campaigns on Orange Star on the southern island of Orange Star and southeast Blue Moon, losing both times. With the Orange Star forces arriving from the east, Drake and Eagle fail to take out the advancing Orange Star forces until new intel from Sonja of Yellow Comet gives them an alliance against Sturm. Sturm is defeated in the Cosmo Land War.
Yellow Comet
Color: Yellow
Training Missions: Nonexistent
Campaign Mode: 3rd Enemy (Controlled in final mission)
War Room Mode: 3rd Enemy
Versus Mode: 4th Army
Resemblance: Japan
Headquarters: Japanese Palace
Yellow Comet CO Leader: Kanbei
Available Commanding Officers: Kanbei, Sensei, Sonja
Brief Bio: Yellow Comet forces were inactive in wars until Black Hole forces struck Green Earth. With forces on alert, Orange Star invaded Yellow Comet to chase Olaf, leaving a devastated Yellow Comet army in its midst. Kanbei and Sonja were defeated, and the Orange Star forces moved into Green Earth, where Sonja figured out Sturm was the real enemy. The Allied forces, including Yellow Comet forces, defeated Sturm.
Black Hole
Color: Black
Training Missions: Main Enemy
Campaign Mode: 4th Enemy
War Room Mode: Nonexistent
Versus Mode: Nonexistent
Resemblance: Alien Country
Headquarters: Something that shoots up to the heavens
Black Hole CO Leader: Sturm
Available Commanding Officers: Clone Andy, Sturm
Brief Bio: As the most technologically advanced and most powerful army, Black Hole is quite a force to deal with. Forging an alliance with Blue Moon to create conflict in Cosmo Land, Sturm led Blue Moon forces to attack Orange Star while he attacked Green Earth, failing. Sturm's strategy was dealt a great defeat when Yellow Comet intelligence figured out the real cause of the war, and Sturm was defeated quickly by the Allies.