Who should show up on next season's "Supergirl"?
An interesting list from Screenrant. My thoughts on their suggestions:
Krypto: Um ... no. Not only is Krypto tightly aligned with Superman, it's kind of a goofy character, too, tipping things into more kiddie fare than I think Supergirl deserves to be.
Mr. Mxyzptlk: Um ... no, even more so. Although he's perfect for a TV show and for Supergirl (I give him the highest chance from this list to actually show up, in fact), I really dislike him as a character.
Valor/Mon-El: This would provide some possibility of romantic complications for Kara, and isn't all that bad an idea. It would almost certainly have to be a temporary thing (with time travel or dimensional alignment coming into play), otherwise Kara stops being unique.
Legion of Superheroes: Hell yes. It's already been hinted at during a visit to the Fortress of Solitude (downchecks to the TV show for not having the giant key). The biggest problem here would be who to restrict it to. The nice thing about the Legion is that stories can go in both directions (present or future), and you can always time travel back to the status quo when the story is done.
Mary Marvel: It's an intriguing idea, though I suspect WB has bigger plans for the Shazam universe. The other danger is that, while Mary would potentially "get it" about Kara's life, her power set is too close in effect (if not in origin). Still, there are possibilities here.
Selena: Um, not. Shout-out with Kara's adoptive mom notwithstanding, the less the movie gets referenced, the better.
Stargirl and STRIPE: An interesting idea, especially as a potential series spin-off.
Big Barda: I love Barda to death, but WB is not going to let Supergirl mess around with Kirby's Fourth World, esp. if Darkseid is going to show up in the JL movies.
Batgirl: An interesting idea, if WB goes for it; the idea of creating a Batman/Superman dynamic, only with the "-girl" versions, could be intriguing. But do we then openly acknowledge Batman on this world, and does that mean yet another heavy-hitter that is never called in when earth-shattering dangers arise?
The Question: Only if he's the crazy (or is he?) conspiracy nut from the JL cartoon, because that guy was awesome.
Power Girl: The idea of Supergirl dealing with an older version of herself from another dimension could be interesting. (A reprise of the JL cartoon's compromise of Galatea -- a forced-aged Supergirl clone created as a weapon against Supergirl would fit even better.)
Miss Martian: Not sure there's room for her and her uncle in the mix, and I doubt she would be nearly as charming as her YJ iteration.
Lori Lemaris: No. Supergirl does not need mermaids. No.
Comet: Okay, now you're just screwing with my head. Kara does not need an intelligent, super-powered
centaur horse (who is secretly in love with her). That just gets -- weird. Just ... no.
Superman: While I admire the desire to keep Kara on her own, the hoop-jumping the show has had to do to keep Superman off-screen even when the story demanded Superman show up has been highly distracting. I'm not sure how to make it happen, but the show needs to do something to resolve that situation.
One additional thought here. One of the interesting things about the Berlantiverse on the CW has been the ability to bring in a wide array of villains / guest stars. Someone who might be good on The Flash can show up first on Arrow if the story makes sense, then go on to the other. That's not as easy with Supergirl being on another network (and another dimension), so how to you split the baby for characters that are not part of one of their specific rogues galleries? Or do you not care and allow there to be different dimensional versions of, say, the Parasite?
(Though, heck, for folk like Mr. Mxyzptlk, there's no reason he can't visit both universes ...)