Weltall Zero
Member
BTW what should I do with useless one-star units? Should i max their level and sell them?
That's your issue right there. I was wondering how anyone could run out of unit space of all things.
Keep only one of each unit, two at most if you want them for specific things (I keep two Eldin for stealing and two Rizers for the dragon). Merge together identical units to raise their trust by 5% per merge. You can also level them up and sell them, especially now with the cactuars.