Japan already gotten the Collaboration and GameWith site has Superman and Supergirl sample teams up. You can also search "スーパーガールPT" for Supergirl or "スーパーマンPT" for Superman in YouTube and filter to the latest dates to see them being used. This video by Sion Wong, in particular, shows a Superman REM-heavy team clearing the DC Collaboration Dungeon very quickly!
An alternative way to get more Superman sample teams is to make use of Wukong, Dark/Light Batman sample teams, Supergirl and Thor (replace Green Zhuge Liang with Flash. Edit: On hindsight, the recover stats are a little low for this team, which is why the similar team suggested over at the Superman's page uses the Light Wizard instead of Athena) over at GameWith. It turns out that Wukong goes very well in Superman teams and vice versa. Superman and Dark/Light Batman are also fairly compatible pairings of leaders other than Superman's active not helping Batman's much. Superman is just a very versatile leader.
He also has quite a number of farmable subs, other than Light descend monsters. I notice Tornado Holy Dragon has a similar active to Baal so its a decent non-REM replacement, though with much weaker awakenings, to use with Superman's active to get a board of red and light orbs. High Light Ninja is another alternative but is much weaker being 4-stars. I did not list the other skill-up monsters as they only went up to level 70.
Good luck to everyone rolling the DC Collaboration Egg Machine!
