For you "In-game cookie" fans, there is a nice dreadnought that you can try and kill. It continuously spawns in Frigates that uses energy transfer on it (And themselves) in order to destroy you. I cannot be soloed, in a full group I'm sure it could be killed...
When you first arrive at the tethys location they are fighting off a bunch of klingons. You need to target the tethys and ignore the klingons using your weight of fire and destroy the tethys also ignore the enemy frigates concentrate on the dread the rest is easy!!
I found that ignoring the frigates is the best way. Concentrate on the DD as that is the guy that is bringing in all those frigates. If you keep taking out the frigates and ignore the big guy you will have an almost never ending flow of them coming in until he takes out the klingons and then they all focus on you and you die very quickly.
Once you take out the DD, you can then focus on the frigates and they are very easy to deal with.
while finishing up the "diplomatic orders" mission, I soloed the tethys dreadnaught, at lieutenant 3. the name reminds me of a raptor in WoW. anyways, it wasn't too hard, but just took a while. I didn't notice that I was supposed to fly over to the npc fleet so they could help me (hence the circle on the map labeled "evasive manuever"). At first I thought it was a glitch when they didn't fly over. oh well, it was fun winning a fight I wasn't supposed to win alone. it's nice that cryptic made that possible.
I'll mention that I used tachyon beam and beam overload back to back to knock out the shields and hit the hull with torps (multiple cooldown cycles). emergency power to shields to stay alive. no batteries required.
Well, the Tethys Dreadnaught and it's allies have always been gunning for me ever since the mission began, and I cannot do a thing about it with my Miranda-class ship, Pegasus, without getting killed. And I have to agree that having a few friends alongside you during the mission would do the trick.
The mission is designed to be soloed. Simply attack the Dreadnaught and ignore the frigates. After you and the Klingons take down the Undine then you can focus your attention on the frigates. It's not a short one-hit battle but I've done it with 9 characters now and never once lost.