Traag is the leader of Krang's Stone Warriors in Dimension X. He was after the Neutrinos (kids) because they were trying to stop the war in Dimension X (before the Technodrome was sent there by the Turtles). He was last seen in Turtle Trek in a scene with Shredder and Krang then wasn't shown again, especially when the Technodrome fell into that plant pit.
The Ninja Turtles Network at http://www.ninjaturtlesnetwork.com has a few eps at a time to download. I can tell you now that Traag was in:
Hot Rodding Teenagers from Dimension X
Shredder is Splintered
The Big Break In (possibly)
The big Blowout
Four Turtles and a Baby (possibly)
Rock Around The Block
Wrath of the Rat King; and
I hope I haven't missed any!