How they were made?
They were made by Mario in forms of Luigi to do chores for him while he sits back on his massage chair and eats Toad Truffles. When he wasn't moving for a while after eating too many Toad Truffles, the Repo Depot released them into Soviet Russia and they took them in. When he was moving, he infiltrated Soviet Russia and took them back.
Involvment in the Katsu War
They were used by Mario to hold back the German Weegees using Katsu in the Katsu War. Most of them died, but the war was over and everyone was happy.