I'd say, this season had exceptionally easy conquests.
Curses! (350 Cursed chest kills) https://youtu.be/1PRjgf3yBEE
Incredibly easy, just restart until you find the chest in Paths of the Drowned.
Find some people, start event, spam aoe. Did it with a single friend, neither of us had constant aoe. We got it on our first try.
Can probably be done solo, especially if you're a DH.
On a Good Day (Three Legendary gems to level 65)
Again, incredibly easy. Will require a bit of work though.
Any Class, any set, should be able to clear Grift 65 with relative ease.
And that's all you need to push gems to 65 with a 60% chance.
Boss Mode (Kill all bosses in TX within 20 min)
Any 4 players, should be able to complete this one without to much trouble.
Basic planning on boss split, alter build for mobility.
Make sure you send someone with good damage to down the tough bosses quickly (Diablo, Malthael etc).
Speed Demon (Clear a TX Rift within 2 minutes)
Moderately easy. You might need a couple of attempts.
You'll need 4 players with some decent speed & damage (Can be done with less, but easier with a full party).
But the only hard part (hard=time consuming) will be fishing for a good rift.
You'll want one with high density and a lot of champion/rare packs (Graveyard, Act 5 Exterior or Jail to mention some).
Find the right rift, split up and wreak havoc.
Divinity (Grift 75 solo)
Should be doable for most classes and sets. Might need a couple of attempts, I cleared Grift 75 on my third try.
You will need some decent equipment, but nothing extreme.
I cleared it with 4 Ancient pieces (Weapon included) and Paragon 580 while playing Leapquake Barb.
Obviously classes are a lot different on how they handle solo rifting, so some classes might have a harder time. Thus needing even better gear.
Also, a solid tip.
For an easy conquest, complete the Cursed chest one on the "other" difficulty.
I didn't actually take advantage of this. But would've been easy to do.
Already had a level 70 HC character, that was needed for Journey. Joined a bunched of HC communities and shamelessly, but politely asked for a boost.
Shouldn't be to hard to find a friendly player to help you with the conquest if you fish for the Paths of the Drowned chest.