An endings guide can be found here:
http://nierautomata.wiki.fextralife.com/Endings+GuideNote, however, that after you beat the game for the third time, you unlock an in-game achievement store, where you can pay in-game money to unlock achievements. Given that by the end of the game you'll likely have excessive amounts of money, paying 200,000 G for this should be a cinch - doubly so given that you can just load your game again afterwards and avoid paying anything at all.