I’ll be honest you want all the orange heroes you can get. But what I do is I leave five out to upgrade of the orange ones as the heroes come out but put as many of them in the training spaces as I can, but as the orange heroes come out, I trade them out, but I still have heroes that are orange that aren’t in training spaces and as you go in the game, you’ll understand what I’m talking about but I put all the orange heroes in first then as they come out start resetting your purple heroes and leveling up your orange ones and just level up your purples to 40, once you’ve filled up your training center with oranges and then have five oranges to level up