I openly welcome the retesting of both Durant and Cresselia.
Cresselia would give a decent solution to all of the offense in the tier and give a sure fire Nidoqueen counter that stall would surely welcome. Cress also makes offense better at the same time, being an excellent Dual Screen + Lunar Dancer to let offense get set up and even recover a fainted mon that can wreak havoc. Moonlight isn't the most reliable means of healing in upper tiers but in this case it only matters if they are running manual weather. Although kinda slow, Cress can also run an offensive set similar to what Uxie does, or run Substitute + Calm Mind with incredibly bulky Subs, in conjunction with hazards + a Pursuiter like Escavalier or Spiritomb to remove Haze Cryogonal. Cress would also diversify the tier slightly more by causing a rise in mons like Escavalier, Scyther etc.
Durant, on the other hand, helps offense by being able to check a lot of random shit provided it can hit its attacks. Superpower / X Scissor / Iron Head / Rock Slide check random threats like Lilligant, Kabutops, Moltres, Nidoqueen, and others with prior damage. Granted you won't be able to run them all because you definitely need Hone Claws but oh well. Unbanning Cress and Durant at the same time would "sort of" offset each other, since Durant does a pretty decent job vs Cress etc.
Unfortunately this is mostly theorymon because i wasn't around for Durant / Cress era but hey it seems like it'd be cool to have them around again and change up the meta :)