Gandalf was a Maia diminished and constrained. That was the deal when he became a wizard. He was pretty lucky to overcome the balrog as Gandalf the Grey, IMHO.
To quote Obi Wan, in my experience there is no such thing as luck. Gandalf expected the balrog to step on the bridge and Gandalf expected to break the bridge sending both himself and the balrog to the bottom, perhaps thinking he could break it as he did leaving himself on one end, as happened. I think you are right. No one ever took on a balrog without dying in the attempt. That the balrog fell in water, that Gandalf was the bearer of the Ring of Fire, had a good sword, etc. were all fortuitous, but the self-sacrifice to stop his counterpart was the key. That and his perseverance.
The eldar Elf lords are supposed to be pretty potent. Glorfindel killed a Balrog in single combat in the first age, as did Ecthelion.
Bossed around, probably not, but they might well have made some sort of alliance.
Gandalf speaks of something similar: if the dragon, Smaug, had not been killed, it would have been wreaking vast havoc in the north during the War of the Rings, keeping much-needed forces from assisting the defense of Lorien.
Likewise, if Sauron could have persuaded the Balrog to go out the western doors and make an approach to Rivendell, the Northern Rangers might not have gone south to link up with Aragorn.
Strategery! (Anybody else fond of the “Risk” Middle Earth variant?)
And both paid with their lives, as did Gandalf.
Nice that both Glorfindel and Gandalf got resurrected. I assume Ecthelion did eventually, too. Though he could still be cooling his heels in Mandos.
The Balrog has been in hiding and will stay there until Morgoth returns. The dwarves and orcs are little more than mites disturbing his sleep.
I remember an annex in LOTR mentioning that a new mithril lode in Moria was discovered after the war of the ring.
I thought they stayed with Snow White.
StG
There was a very embarrassing falling out.
Yeah, he was subscribing to Middle Earth-link.
They need to adjust their stroke distance then. 
No, the Eldar are an entirely different franchise.
And just where do you think Warhammer shamelessly stole the word from? “Eldar” is what the Elves call themselves.
Huh, I thought I was just making fun of a typo.
That’s the funny thing-- It probably was a typo, and yet manages to be exactly right anyway.
Celeborn is frequently referred to as “the wisest of the Galadrim”. Based on his character in both the book and the movies, I have always thought that this did not speak well of the intelligence of the Galadrim.
Nah, Galadriel and Celeborn just have an agreement, one of those that married couples often have. He doesn’t argue with anything she says, and in return, she goes along with the pretense that he’s the wise one. The truth of the matter would be unkind to his ego.
Well, Olorin is referred to as the wisest of the Maia. Pretty hard to sell that when he didn’t spot Saruman’s treachery coming, or that Bilbo’s ring was the One Ring. Or leaving Frodo guarded by a fellow with only a broken sword who wasn’t even in the same county.
I keep wondering how things would have turned out if Tolkien had decided to keep the Telerin name and refer to him as Teleporno.
I briefly considered that name for SDMB when I first registered. 
I believe that Arien, at least, drove off several Balrogs from the Sun. She may not have slain any of them, but she certainly survived.