Hi Math,
I'll elaborate a little bit.
IMO, underworld are best against elfy teams, who don't really want to get stuck in.
Bashy teams can be much harder to handle.
But that might just be due to the way I developed my team:
http://www.midgardbb.com/MBBL/teamView.php?teamid=577
I'll try to explain my skill selections:
In theory, on doubles, I'd give all the skaven dodge, except a thrower who'd get strong arm. The troll would get block. And the gobbos would likely get guard.
Blitzer #1 got 2 AGs fairly early, which kind of changed my plans for him.
I've been suffering from lack of tackle as a result.
On normal progression, I think I'd have taken tackle on both blitzers.
And I would probably have developed one of them as a basher - mighty, piling, claw.
Blitzer #2 got dodge early. Suited me fine, as I think the Blitzers belong on the LOS against most teams (not the bashiest ones though). I think AV8 and block gives them a good chance of survival. And you want your line to survive. If it goes down, you're headed for a 1-2 grind.
Thrower #3. Extra arms first, for stability. Then accurate. After that I took Kick-Off return, which has worked surprisingly well. And it helps on OTS attempts! I took leader last, but there were other candidates. IMO, this team doesn't really need that many rerolls.
Thrower #4: Extra arms also. He then took block, which has served me well (alongside the Guard blitzer) against wardancer types - and for back-up blocking. He then took nerves as a reciever type - and I haven't had much use of that! He plans to build with dump-off later though.
Lineman #5: I'm very conservative, so my linemen have skilled up slow. Thos one got dodge, se he is headed for blodge.
Lineman #6: Took wrestle, to help offset my lack of tackle. He'll take tackle next I think. Who ever gets to 3rd skill first will get either kick or possibly frenzy.
Had my team developed differently, and knowing that bashy teams are my main problem, I think I'd go block, claw, dauntless with both of them.
Troll #7: Tentacles first, and it has been a great equalizer. Stand Firm and Guard are a high priority too - but I'm kind of leaning towards Piling On (then Claw?) now. When he finally does land a blow, I want it to hurt! Not only that - but he has developed very slowly, and Piling On could help him on the way to his third skill.
The gobbos: I've tried a little of this, and a little of that - but if I had to do this again, I'd go with more 2-heads. This is a mobility team, and every turn of every drive, you'll wish you had more 2 heads. Simple as that!
That being said, I took:
#9 sidestep. Which has been OK against the occasional frenzy threat, but not a big hoot.
#10 ST+

. Horns, then 2 heads are next

#11 sneaky git: Others swear by it. I've been disappointed. I'd go with 2 heads instead.
#12: Took horns early (as a threat) - then rolled a double: Wrestle.
On any other gobbo, I'd probably have taken guard on the double - that'll help your horns guys and other players a lot!
#13: Took catch early. 2-heads would probably have been better - but catch has had it's uses. I've used him to skill up MVP gobbos with quick passes. Other than that, he sits on the bench and waits for the occasional OTS attempt. Which is why he has MVPd his way to extra arms.
#14: 2-heads (Yay

) - then big hand is a classic combo.
Given more time, I'd say 2-heads horns, 2-heads big hand, prehensile tail diving tackle and 2 heads disturbing presence are the 4 basic combos to go for.
Cheers
Martin