According to commentary on the Mulan DVD, these three essentially represent the entire Chinese Army. They presumably were recruited via conscription notice, similarly to Mulan. As soldiers in the Chinese Army, they are capable of fighting using various methods, including swords, cannons, arrows, and hand to hand combat.
Yao, voiced by Harvey Fierstein, is the shortest of the trio. He wears a red uniform, and also has one black-eye as well as a mustache. He seems to have a hot temper, which can be cooled by Chien Po. Despite his strength, he seems to be somewhat clumsy. He initially dislikes Mulan, in part due to a perceived insult (which actually came from Mushu), but later becomes her friend.
During training, Yao talks back to Li Shang, and as a result is picked out as the first to try to retrieve the arrow, deliberately humiliated in front of the other recruits.
In the second film, he wears purple and falls in love with Princess Mei. He is able to impress the princess using his talent for fighting.
Ling, voiced by Gedde Watanabe, is of medium height and slender build. He is usually seen in a yellow uniform. He appears to the the clown (and de facto leader) of the group, and often has a joke ready. During training he slyly kicks the support from 'Ping's' rocket, resulting in her becoming charred and Chi-Fu's tent (and Chi-Fu) to be incinerated by the wayward rocket. When Mulan proves her worth, he is the first to intend to start over - unfortunately this is during her bathing scene. He nearly discovers her secret, but Mushu bites him on the backside, causing a panic among the trio that allows Mulan to get away.
He is something of a weakling physically, as he knocks himself out during a block breaking task in training. he does grow more capable though, as near the end, he is able to use the move to incapacitate one of the Huns.
In the second film, he wears blue and falls in love with Princess Ting-ting. His talent at telling jokes is able to win over the princess.
Chien-Po, voiced by Jerry Tondo, is the largest, in both height and size, of the trio. However, he is also very gentle, and seems to care a great deal about food. He wears a blue uniform. Some of his character appears to have been taken from Buddhist imagery. At times, he seems to demonstrate super-human strength.
After the camp turns on 'Ping', Chien-Po is the only one of the trio to not try to make life difficult for Mulan, although at no point during the sequence does he show her any support.
In the second film, he wears green and falls in love with Princess Su. They bond over their shared love of food.
In Mulan, the trio are first seen in the camp. Their interactions imply that they already know each other. While Mushu's advice to Mulan is initially helpful, Mushu insults Yao, who starts a fight believing Mulan said the insult. Since 'Ping' earns all the recruits a harsh punishment, the trio quickly take a dislike to the disguised Mulan, and continually harass the soldier. Ping is able to win their respect after completing Shang's challenge. One night, they reintroduce themselves, in order to make a new start. However, they do so while bathing, making Mulan very uncomfortable, as she is forced to hide her gender. Due to some quick thinking by Mushu, the three remain unaware that "Ping" is actually Mulan. The trio are able to successfully complete their training, and are called off to war with the rest of Shang's troops.
In order to keep up morale on the long march, Ling encourages everyone to begin dreaming of the girls who are surely waiting for them back home. Ling dreams of a girl who is pale with eyes like stars. Yao dreams of a girl who admires his strength, while Chien Po doesn't care what his girl looks like, so long as she can cook well. However, the scene comes to a close when the come upon a village that has been destroyed by the Huns. The three are sent to search for survivors, but they are unsuccessful. However, Chien Po finds the body of Shang's father, General Li, and brings back the general's helmet as proof.
Shang's troops begin pursuing the Hun army, and they are drawn into battle after their position is given away by an exploding cannon. When Mulan runs with the last cannon in an attempt to destroy the army, the trio follow. However, they retreat just as quickly to the safety of a rock formation when they see a large avalanche, started by Mulan's cannon, coming. Yao shoots an arrow, with a rope attached, to save both Shang and Mulan from falling off a cliff with the avalanche. Unfortunately, the rope slips through his fingers. Mulan is able to grab the arrow, and shoot it back into Yao's hands. The troops attempt to pull Shang and Mulan up, but struggle until Chien Po comes and picks up the entire unit and pulls them up.
The trio are later seen pacing while "Ping" is being treated by the medics, and are visibly shocked when the soldier is revealed to be a woman named Mulan. They are forced to march off to the Imperial City, leaving Mulan in the mountains. As they reach the city, they are shown to be saddened about Mulan, despite being welcomed as heroes. When Shan Yu reveals himself, Yao leads a charge to stop him. However, the Hun leader is able to kidnap the Emperor. The doors to the palace are barricaded, forcing the army to try to ram the doors down.
Mulan appears, and announces that she has a plan. Ling, Yao, and Chien Po choose to follow her, followed by Shang. Mulan is able to sneak herself and the trio into the palace dressed as concubines. The group is able to take out the Hun guards, as the Huns let down their guard around the "concubines", allowing Shang to rescue the Emperor. Chein Po escapes down a line of lanterns with the Emperor, followed by Ling and Yao. However, they are forced to look on as Mulan becomes trapped with Shan Yu.
After Mulan has defeated Shan Yu, the trio come to protect her from Chi-Fu's rantings. They are among the people who bow to Mulan as the hero of China.
In Mulan II, it is revealed that the trio has been unable to find brides, and also seem to have been given little credit for their roles in saving China. They go to the Matchmaker, but are promptly rejected. Soon after, they are recruited by Mulan and Shang for the job of escorting three princesses to the kingdom of Qui-Gong. Each one of the trio falls in love with a different princess along the way, and they take the princesses to a carnival. Their feelings are later found to be mutual, and the Princesses become hesitant to fulfill their duties. In Qui-Gong, however, the situation is resolved as Mushu, playing as the Golden Dragon of Unity, gives the Princesses permission to marry whom they want.
Role in the series
The three soldiers reprise their roles from the films, but they also serve as reinforcement allies to the Shell Louge Squad, otherwise, not really members, just allies when needed.