I was thinking a Necro/Paly would be a combo for the undead nukes, snares, mez, slows, and roots however that only thing that worries me is the healing. The Paly heals aren't that great, and while I'll have some form of lifetap DoT on the mob so I can twitch heal, I just don't know if that will be efficient.
In a Nec/BST, later in game, the heals come from the BST but not for himself, for his pet. My nec's dots would be overpowering, that taking the BST soloing have to tank, pet tank, tank, pet tank would never really be taken into consideration. I've played that on my BST before, I don't know how PoP is, but I would send pet in, tank until I got to 80% sit back, nuke, regen, go back in, until the mob was dead. Obviously not a good thing for summoning mobs, as I hear, but coupled with the Necro's dot's the mob would go down much faster. Maybe there's something i'm missing, but as of now on my Necro, the way I pull is snare, dot, fear, send pet, finish dot line, sit. Wait a few ticks, pull second mob, and start over. I usually have two mobs running around, and they are usually 50-70% health difference so I never get any oh ship moments.
However, like also mentioned, the amount of spells needing to be cast, playing on two computers would be the best way to do that, and I only have my laptop, and a desktop PC. Possible to do, so I hear.
I'm going to have to sit here and agree that the Drui/Necro or Dru/BST is my best option. Preferably the latter. The amount of content that can be duo'd would be intense. I will be honest here, I started the necro just to find a path to get to 65, and to kind of farm to twink my real toon, my real favorite class, beastlords.