Board Thread:Questions and Answers/@comment-70.122.243.44-20141206013220/@comment-24802125-20141207082642

You don't necessarily have to have good units to rank in some events, but it'd be very preferable to in most. Otherwise, some event clears can be quite difficult, such as the Folly in the Forest's Bonus Area.

Players usually get stronger by collecting whatever event units they can muster in addition to progressing in the main questline. It's just a matter of effort and time before you're finally able to start ranking or completing hard event challenges. Good luck. The Raid Boss Season units are usually the most accessible to new players.