A Perfect Clear (PC) means having no filled cells left after a line clear. The Tetris guideline rewards such an occurrence. Usually, a PC sends 10 lines in multiplayer (whereas most games will not send additional lines from combos, T-Spins and clearing multiple lines at once). Perfect Clears can only be achieved after a minimum of 4 cleared lines at the start and they can only appear after an even amount of cleared lines, if no garbage is received.
There is one basic setup that is used to start the game with a Perfect Clear:
Note that getting a Perfect Clear is not guaranteed with this setup. The chances just lie around 61.2 % (the chances can be increased a little by leaving the first I piece on hold). 3 of the first 4 pieces of the second bag are used to complete the 4 lines in one of the following ways: