Killing dclone with a Skelemancer is simple, but not a 30-second job. I've done it several times.
First of all, you do not need "godly gear".
Here is my Skelemancer, and he does just fine.
There are essentially three main parts:
1) Spawn him. I like to use the superunique at the tristam portal --- easy to find, free space, a useful portal (see below), and style points for the location.
EDIT: 1.1) If it's your first time, you might want to let him finish off (most of) your army, so you can see how much health you can take off him with one army, as "preparation" for step 3.
2) Retreat and get revives with crushing blow. The usual candidates are Urdars from River of flame, Maulers from Durance of Hate, Blunderbones from the palace, Thorned Hulks from Kurast and possibly other beasts.
2.1) Let the revives beat dclone to a pulp. Essentially, let them take him down to a pixel or two.
2.2) If your revives can't handle it, get fresh ones
2.3) Make sure you have poison magi --- they get insane poison duration. Also, if your merc has poison damage, make sure the poison from your magi is in effect when retreating
3) When the clone is down to just a pixel or two, retreat, raise a full skelly army, and finish him off.
At all times, keep him "gumbied" and decrepified. Don't worry about your merc, he's not important for the crushing blow phase at all, jusr revive him for the final stage.
I spawn him in a 1-player game, but then I move in a mule to make a portal in tristam --- that way, when getting the revives, I can tp back to town without loosing my portal to the clone. Running back to the wp usually doesn't work, since the revives will vanish. I only skip this "mule portal" if the stony field waypoint is next to the stones.
Another option would be to spawn him in place of Eldritch since he's almost sitting on the waypoint, but it's much better if there are just act 1 monsters in the vicinity.
EDIT: as for myself, I hardly ever get hit by anything the clone does. I just keep my distance, and try to avoid standing in the direction he's casting his breathweapon. If he does cast it my way, I just move out of the way.
His Armageddon is completely harmless, since it rains down around him, and that's NOT where I am.