Halinn

If being a drab is enough, she could just give Vasher all her Breaths, then have him give them back after she's bonded.

Allomantic brass/zinc + feruchemical duralumin. The ultimate in social abilities

That's more or less how I'd put it as well, asterion. It's not that easy to accurately place Marvel characters, because they can vary extremely much in competence and power from one appearance to the next, to fit the story. Particularly characters in the Herald tier fall prey to this, as they're weak enough to appear alongside "normal" superheroes, so they have to get occasionally lose to someone on the level of their teammates to make the threat seem stronger. And sometimes, they get ridiculous feats, such as the Silver Surfer traveling millions of times faster than light, or making a black hole.

The One-Above-All is an entity more powerful than Adonalsium. Remember that the Cosmere is a dwarf galaxy, where OAA is omnipotent in multiple universes. The Silver Surfer would probably be a good match for something like the Stormfather. Above him is someone like Thanos, who a shard would be hard-pressed to stop if he wanted to destroy their world. Above that is the cosmic level, where I'd place Adonalsium. This is where Odin, Dormammu, cosmic cubes and that kind of thing are (Odin on the low end, cosmic cubes on the high). The thing is, Marvel has like 4 levels above that. Representatives from those in ascending order would be Galactus, Eternity, the Infinity Gauntlet, and the One-Above-All

That's respectively no and maybe. Cosmic level Marvel characters would definitely count as heavily enough invested to survive shardblades.

Feruchemical duralumin and/or aluminium + Forgery. Identity and connection seems like it'd make you really good at Forgery. Possibly allomantic gold as well, to know yourself better.

Assuming she has a big enough anchor. The thrusters can pull some heavy lifting, possibly even more than her maximum power

You've steelpushing/ironpulling for some very interesting movement/combat abilities, emotional Allomancy which is super cool (and one of the powers I feel is relatively underrated on these forums), time shenanigans and you can get to see your past/future. Now, for Feruchemy, I just don't think it offers that much besides nicrosil hacks.

For me, it's because Hemalurgy is not well defined, and Feruchemy is not really that interesting by itself. There are tons of interesting stuff to do with combinations of Feruchemy + X, but I feel like the limits it has when being solely by itself make it not the best. I had Allomancy at my top because it has a number of versatile uses, covering a lot of bases. Forgery would be my number 2, though. Changing things as fundamentally as can be done with that is a really cool thing.

Just thinking about it narratively, it would cheapen the uniqueness of Captain America's shield if a weapon there are hundreds of could cut it. But it might make for a good scene if it had withstood a ton of blows from dead shardblades, but then got sliced by a living one.

I suspect that Iron Man's flight and repulsors would let him outrange Vin, but she might be able to take the victory by surprising him with emotional allomancy and/or duralumin. I put it 7/10 in Stark's favor.

If it's not a shardic influence, perhaps it's a worldhopper who wants to figure out how people are different on the different shardworlds.

On the subject of combos with Forgery, I imagine that Feruchemical Duralumin would be really good. Tap Connection to better understand the object you're forging. For forging yourself, maybe Feruchemical Aluminium would be better, but we haven't really seen many examples of Identity in the books so who knows

Gotta be double zinc. I think few things match up favorably to the power of unlimited mental speed, particularly when you've rioting to go with it. If I had to choose some non-compounding combo, I'd still want feruchemical zinc, but there are a number of good options for the allomantic side. Brass is an obvious one, be more apt at choosing the correct emotion to soothe. Pewter is interesting in that you can act the dumb thug, but be able to tap zinc to really surprise people. Burning electrum while tapping zinc might let you consider the implications of the shadows you can see really well. For other strong compounders, steel and chromium always get mentioned when this comes up, but like hoidhunter said, knowledge is power, which is why I prefer zinc.

My favorite theory is that Hoid is using the bead feruchemically. WoB is that he originally took it because he wanted to become an allomancer, but that he didn't burn it. This suggests to me that he figured out that it can be used in other ways