Outland Raider

Considering Karazhan, Zul'Aman, Mount Hyjal, and Sunwell Plateau aren't located in Outland, wouldn't it be more correct to name this "Burning Crusade Raider?"

Or "Burning Crusader", perhaps?

Remember that backflagging for these achievements will only occur if you have loot from the boss (if it's a 25 man raid) or a quest associated with the boss kill. Assuming you've done every attunement quest and have a Blessed Medallion of Karabor you'll have all of the 25-man achievements sans Hyjal and Sunwell.

Archimonde has no quest associated with his death so you'll either need to kill him post 3.0 or have a drop from him.

Karazhan credit can be accomplished by having done the quest A Demonic Presence or just slaying Prince post 3.0.

Zul'Aman credit can be gained by turning in Zul'Jin's blood or killing him after 3.0 hits.

Finally, if you don't have a drop from Kil'jaeden you're out of luck unless you kill him after 3.0 comes out.