Remember, this is not me suggesting these...
I'd do the following:
Tier One: Superstar for Superstar
Prospects Division: Rhett Lowder for Jackson Holliday
Big-time trades take big-time... guts. Lowder's been nails, while Holliday struggled greatly in his first cup of coffee. That said, he's absolutely loaded with talent. This would be a case of trying to strike while the iron was hot and would likely take a second prospect as well. (I'm guessing Edwin Arroyo might do it, though he might not.) Still, Holliday is the only reason I'd consider moving EDLC to another defensive spot-- likely 3B, with Marte moving to RF when he comes off the suspended list. Unlikely? Of, for sure. Impossible? Probably. But that's what it'd take to get me to part with Lowder at this point.
Tier Two: Division One Starters
Andrew Abbott or Graham Ashcraft for Ryan Mountcastle, Heston Kjerstad or Coby Mayo (AAA)
Mayo's killing it in AAA and has all the attributes CES had last year. Kjerstad just has "it"-- it seems like he's a tough out I hated to see up to the plate this weekend. Both will be better. Abbott or Ashcraft makes some sense, then, as a partner. It'd hurt short-term to see one of them go. Long-term? The Reds probably win that trade.
Tier Three: Division Two Starters
Brandon Williamson for Ryan Mountcastle
Mountcastle is a solidly average OF currently playing above his pay grade. Speaking of, he's going to get expensive relatively soon. I'd guess Baltimore might be inclined to get more playing time for its other players at the expense of a relative spare part. Mountcastle is that. For the Reds, he'd be a fine LF/ DH/ 1B option and a RH hitter.
Tier Four: Maybe for Maybe
Chase Petty or Connor Phillip for Sam Basallo
Petty and Phillips have been major disappointments. I'd consider just about any Red pitching prospect aside from Lowder at this point. Basallo is a 19-year-old holding his own as a catcher in AA. It'd likely take both Petty and Noelvi Marte to make that deal happen, but I'd do it gladly.
JAG for JAG
Lucas Sims, et al, for Ryan McKenna
Relievers are fungible, and Baltimore might well need more as the season wears on. Dealing for McKenna strengthens the Red bench. (I loathe Bubba.)
I hope the Orioles would hang up the phone laughing at any of these proposals.