I don't really have a list, per se. It's simply a matter of having "enough" of any given aspect. For instance, you don't need a tanker if you have enough buffs/debuffs and those with them are proactive or responsive enough. You don't need a huge amount of raw damage if you can drop an enemy's damage resistance enough. You don't need a lot of buffs/debuffs if you can sufficiently control the enemies. The problem is that many people often play on PUGs, where there is little communication and everyone is basically soloing in the same instance. Anytime I see these kinds of posts, my first inclination is to ask if you took the time to talk to your teammates, examine your team composition, and derive a strategy that used those resources to their greatest extent...