Why can't I play two players at some games?
You must assign a different player for player 1 and player 2. On the main menu of your console, press "START" then go to "Controller settings".
Configure your two controllers one after the other. The "HOTKEY" button must be assigned to the "SELECT" button, so you will have two buttons assigned to the SELECT button (HOTKEY and SELECT).
Once done, you need to put player 1 on USB #0 and player 2 on USB #1. For PS4 controllers, be sure to put the "SELECT" and "HOTKEY" buttons on the "OPTIONS" button and the "START" button on the "HOME" button.
NEVER leave player 1 or player 2 on DEFAULT, otherwise when launching your game, the console will not be able to assign players, as two players will be assigned to "DEFAULT".