The most important thing is having a way to regen health during the Crota fight.
For the Abyss, all the 31s are going to die, plain and simple. As long as one of the 32s can make it across though, it's all good. I'll be a Hunter so I can give it a go. If Auty and/or Matt are also Hunters, that doubles/trebles our chances.
For the bridge, it'll be very good going if any 31 gets across and stays alive for the Ogres. Really, I expect we'll have to go with getting one across and cheesing with Warlock self-revives. So, we'll need one, preferably two Warlocks for that part.
Deathsinger shouldn't be a problem.
Crota.. Really we need 4 32s: swordman and 3 rocketeers (with tracking rockets). One 31 can keep the boomers entertained and the other can either help out or stand and dance

The most important thing is being able to regen health though as otherwise one or two hits and you're dead, causing an Oversoul which often causes a wipe.
To be honest, I've only ever done it with one 31 in the team. 2 might be just about doable. I'm not so keen on 3!