Gunnr - you'd need 2 tanks of different arche type though, and relatively high DPS, which would be harder to do with needing 2 tanks.
Modrfrost - Just need DPS > add respawn time.
Static mob - DPS > add respawn
(Kraytoc)
Brendegor/illatus
Tert - Need 2 tanks, the turtles could pose a problem...
Kreeger - Just need dps and a bit of quick multitasking
Taaltak - Cake
Eirreen - Not sure with that stun... 2 tank it.
Kraytoc - Would be one wicked long fight, but I can't see why you couldn't 1 group it with ease.
If you have enough dps to get past the first namer in Temple, you can do the first 3.
There's the list of mobs I believe (but haven't done) 1 grouped. However, if you have to ask which ones can be 1 grouped, I hightly doubt you have the gear, or DPS to be able to do them. Many of the DPS mobs require 300k MIN, and more realistically 500k.