Sorry Tsetsuo,
But I have to strongly disagree. I do not think a party of lvl 55+ can beat Shadowlord. I personally think you need to be a minimum of lvl 58+ everyone with melee closer to lvl 60 if possible. The first time i beat it, we were only 5 because the 6th member hadnt finished quest correctly. But at that point we were all 60 with the blm at 62. We had to use drinks and such, because mages were low on mp.
If you have to remember only two things, remember this: the blm cannot be under 58. And whatever you do, you MUST bring a blm. Dont think about going without one.
Apart from that, the strats are fairly accurate on Alla, its a regular fight at first, the second stage is all curaga/nuking.