Regarding W (Wing)'s CHALLENGE Mode

I hadn't properly trained the W (Wing) units and pilots (except for Nator and Pierrot, who I quite like…) But I somehow managed the CHALLENGE mode, except for HARD (lol) Of course, keeping all units alive is impossible! UR Pierrot's EN runs out really quickly… I really want the gacha UR Nator already! (Honestly, I don't have many good memories (or rather, impressions) of W due to influences around me)