Bulky Lass+Swellow+Moltres+Raikou is one of the most broken cores right now. Add in a donphan to set up stealth rock, spin, revenge things like swellow with ice shard, giving you more priority and letting you revnge without revealing swellow or raikou, plus an anti-lead, and you have a solid team. Bulky Lass makes a great pivot outside of the lead position. Say for example I have moltres in, and milotic comes out. I need to get raikou in to revenge. But if it's offensive, raikou could take a big hit from hydro pump. Just go to lass! Set up a layer or two of spikes, die, and bring in the revenger.
Swellow also does awesome with spikes, since donphan can setup on it's counters, and moltres can force out it's counters and since most hate spikes (registeel, steelix, aggron) with a little prior damage (which is easy to get, since these like to switch into raikou who can weaken with t-bolt) next time it comes in, Swellow can just muclse through some, like registeel, while others can be easily forced out again. Seriously, swellow does like 24% to registeel with facade after toxic orb activates and easily 2hkos donphan, but it has ice shard, so you should switch. (based on experience). While swellow is easily walled on it's own (not broken) moltres can easily switch in and fire off flamethrowers to kill (offensively broken) and shares a lot of checks and counters with other dangerous pokemon which it can weaken and stops their other counters. (Support Characteristic). Froslass can set up spikes to easy, everyone and their mothers prepare for it, yet, when used outside of lead (which only i seam to be doing) can easily get up many layers of spikes (support). Raikou, while coming close to offensive and defensive characteristics, is only broken with spikes support-provided by lass.
I've never used dugtrio.
Uberiffic's final verdict:
Moltres: broken
Raikou: If lass stays, broken, otherwise, very close but not broken
Froslass: Fun to abuse, but we need to ban this bitch. Broken
Dugtrio: N/A, but from what ive seen, not broken. Too weak.
P.S. @ roflkip: while usefull for mono-normal, swellow has no business running a set just to stop steels, it can u-turn away, and there are much better steel killers; donphan, moltres, magneton, etc.
P.S.S. I find it funny that when theorymoning, everyone thought dugtrio would be broken and donphan would eventually fall into obscurity. When they came down, donphan ruled, dugtrio sucked. Now, dugtrio is suspect, and I never see donphan. Of course, with yanmega gone, and moltres will probably be gone soon, he has little to spin for. Especielly when he cant touch swellow with the standard (as I see) set of ice shard, earthquake, spin, stealth rock.
P.S.S.S. damn that was a long post.