Of course, the actual tier rankings take a lot of different factors into consideration, including cost effectiveness. Computer-controlled machines are always worth half their normal value. The earlier games had a larger system, ranging from four stars to a half star (590 points to 200, out of 1000 per battle).
It got an even more epic remix in Full Boost as " End of Authority -Revised- ". where you have to fight all 3 phases of the Extreme Gundam.