We follow what is likely the common strategy employed by most guilds.
The initial pull is shown below – tanks are spaced so that they can take turns of the breath attack without splashing the other tank, and taking care not to turn Wrathion so that his tail swipe strikes the melee. For their part, the melee DPS must be tightly stacked. A raid marker to designate the area the players should stack is advised.
Raiders must run their incinerate out of the raid. At this time, there is one incinerate per phase. There is more room to the rear of Wrathion than his front; so melee should prioritise dropping their incinerate in the zones as shown. Ranged and Heals have more options available behind them, and should take care not to overlap a melee player who is running away.
Soon after Incinerate, Wrathion will execute Gale Blast, forcing the melee players to move away. At the same time, numerous small fireballs will be thrown at ranged and healers, effectively forcing all players to move. By now, all players should have zero stacks of Creeping Madness, except the players forced to move when they dropped off their Incinerate.
The raid moves to the appropriate safe zone. After Cataclysm is complete, the raid meets Wrathion in the middle of the room, with the tanks rotating the boss around similar to the initial pull. From here, the fight resumes as normal, with melee moving as soon as they can to a safe zone, and ranged/healers using their better positioning to find their own safe zone.
During the Pillars phase, Creeping Madness disappears. The whole raid needs to move to the side of the room where Wrathion currently is. There is plenty of time to do this before the scales hit the ground and no movement speed abilities are required. Pre-assign players to pick up a specific scale, and designate an area just in front of the boss for your raid to stack on. Drop flares and other AOE abilities to pick up the assassins.
Your scale soakers can soak ten scales each. There are 32 scales, so two will be missed. Take care to collect the pillars that spawn under the boss. Note that if you tag a pillar already tagged by another pillar, it will deduct from your allowed tags with no benefit to you. Therefore, to avoid double-ups, each scale soaker needs to take a moment while the scale is falling to plan their path and make sure it does not overlap.
We have the scale soakers on the sides favor pillars on the outside, while the middle soaker runs through the middle and tags as many as they can.
In most cases, your middle soaker will run out of pillars first, and one (or both) of the outside soakers will need to double back, as shown below. In this image, the two remaining pillars are in the middle of the path, but they could be anywhere.
Because the pillars nearest Wrathion are destructible first, and because the raid was told to move to Wrathion at the start of the phase, your team is in a prime position to eliminate the pillars underneath Wrathion first. Make your way to the other side of the room. Once the last pillar is destroyed, the phase ends. Resume from the ‘post cata regroup’ stage, and repeat until victory.