I think maybe we just don't have access to enough powers to fill the "lol unlimited power" trope of superman. I think Emerald might fulfill the strange outsider (or possibly the leader trope) best. Also since ones own perspective is always the easiest, I vote Johnathan as "the big guy" (hulk or the thing... and I can't really think of an important DC hero that fills the exact same role... Huh. Well, there's a few villains, maybe Solomon Grundy. And there is a thematic link in there somewhere to the 'death' that super heroes go though in farfield.)
Hum. Here's my thought on tropey party structure
1: The Leader. Emerald (Naturally, since she's the mayor. Could also work as number 2 if someone else takes over the leader role and has enough of a personality difference from her. Or number 6 if she turns out to be really alien)
2: The Lancer. Radia (I originally put Wymond here, but he fit much better in number 6, so now Radia. She sorta works because she's a bored party girl, which does nicely contrast with the hard working alien in the first slot. Still, sortaaa a weak pick?)
3: The Smart Guy. Lillian (Naturally)
4: The Big Guy. Johnathan (Naturally.)
5: The Chick. Jack Liefield (His eclectic generally non offensive powers and low stat scores makes me think Kansas character sorta fits. He also is about the closest to this role in my D&D that the party has (although more of a lancer there really so you know) eeyyyyy maybe that'll come over. Kinda a weaker pick)
6: The Weirdo. Wymond (Nothing spells weirdo like a time displaced knight (my guess!) without knowledge modern technology.)
7: The Token Kid. Eins (Naturally)
All and all, I think maybe 4/7 of those are niceish picks (although could break down when we get to the roleplaying, and of course no one fits perfectly), the rest sorta need more information on, or possibly just don't fit well into that structure...