I noticed a video or two with this pairing popping up on youtube, so I did a search for パズドラ キャプテンマーベル and it seems like (with the collab only having been live for two days) Captain Marvel’s most popular pairing is Hanekawa Tsubasa from Monogatari.
If you’re not aware (I wasn’t), Hanekawa is the orb skin card from Monogatari collab, and after transforming she has AS: For 1 turn, bypass att. absorb shield effects; Create 6 Light orbs over non Heal orbs (4cd).
LS: 1.5x all stats for Light Att.; Reduce damage taken by 50% when 7 or more combos; 12x ATK and deal 5,000,000 additional true damage when matching 2+ Light combos.
Ideally you still want your own Captain Marvel to run as a sub, but if you can’t roll/don’t want to trade for her you’ve still got options like Shiranaki as a suitable option, and it isn’t as though you can’t just stall a turn for Marvel’s active either.
Most of the buzz here for Monogatari so far has been around Nadeko, for good reason, along with a little bit of chatter about Araragi. We probably shouldn’t sleep on Hanekawa either, especially since she’ll be very “easy” to obtain (assuming you’re willing to buy the bundle).
There is a bit of risk here though, since there’s the possibility we don’t get the Marvel collab and Hanekawa goes the route of Nero from DMC.
Youtube search results for the lazy: