This has been a "pet project" of mine for the past few months. I'm fully aware of how easy this achievement has become since the release of both cataclysm and Mists of Pandaria; so I decided to make it as hard as possible for myself and my good friend. It took a good few wipes, but we eventually got it down.
Two paladins vs Algalon 10, using the gear requirements as originally set by the achievement. Hopefully this serves as a demonstration as to how easy the boss is now, but also as a demonstration of the strength of paladins and what putting semi-decent play on a well geared character can result in.
Enjoy:
If you've undermanned this boss at any point, feel free to share. I'm not posting this to brag, I just really enjoyed doing it.