Advanced Training, or Te Coman'das Din, was given to a Commando who excelled further than his brothers. The first Commando to receive this training was RC-1138. He eventually became a Commando Paramount who led Delta Squad 12. During the training, the Commando faced things that were much more powerful than the original species or thing. Commando RC-1138 somehow completed the whole training.
Even though many others had been put to the test, none had succeeded like him, until RC-1221. He was the only one to complete the training like RC-1138. The Elder Kaminoans decided to put the two together with two other squadmates, but for some reason the Commandos did not get along. RC-1221 and RC-1138 were finally placed back in their original squad and the Alpha Squad 1 never came.
However, shortly after the Kaminoans appointed Commando Cardinals as the leaders of separate Alpha Squads. Even though the new Alpha Squads would never be as great as the original, they still came pretty close.