The upcoming Avengers movie got me thinking about this. The original team up that formed the Avengers were:
Ant-Man
Wasp
Iron Man
Thor
Hulk
That is a totally ridiculous team up. I mean, look at the scale of power, there.
Well, that's actually not that ridiculous to me. The Avengers was a "dream team", a gathering of unaffiliated popular heroes. They don't have to compliment each other in any way. Redundancy or outright irrelevancy is okay as long as you have clout.
That's in direct contrast to a formula team, which is assembled like a 4e party or a boy band, by filling out various idealized roles (e.g. a strong guy, a smart guy, a stealthy guy, a straight-man, a loudmouth, and so forth). Ant-Man constantly remarked on how outclassed he was (particularly after becoming Giant-Man), and of course the line-up didn't last long anway.
The Justice League is at least as bizarre an assemblage, once you discount the "dream-team" factor. You have a few guys like Superman and Green Lantern who do all the heavy lifting, and then a bunch of low-yield gimmick guys like Hawkman, Green Arrow, and Batman. I think we've all heard our share of jokes at Aquaman's expense.
I always throught that "The Champions" were quite an arbitrary group
Angel;
Black Widow;
Darkstar;
Ghost Rider;
Hercules;
Iceman
and "The Defenders" even more so - with an astonishingly powerful core group:
Doctor Strange,
The Silver Surfer,
The Hulk
Namor
plus a revolving door of others and also-rans!
The Champions actually came about as the formula team nobody wanted. The guy who wrote it just wanted to do a book with Angel and Iceman, but his editor told him to expand it by filling out the tropes ("You call that a team book? Where's your strong guy? Where's your girl?").
The Defenders got started as a dream-team crossover between different comics that become popular enough to justify a series. They threw in Valkyrie because the group needed a girl. The lineup didn't last long, since the characters really didn't compliment each other well.
My favorite wildly-inconsistent group is the Legion of Super-Heroes. You had everything ranging from a handful of Kryptonianesque powerhouses to characters like Bouncing Boy, Matter-Eater Lad, and Dream Girl (whose super-power is actually dreaming). Bear in mind that most LoSH's powers were typical for an inhabitant of their homeworld, so relatively speaking they weren't terribly special. What's that? Saturn Girl wants a raise? OK, well....she's fired. Go to Saturn and get a replacement.
And my personal fave is Triplicate Girl. She could transform from an ordinary girl into.....THREE ordinary girls! But wait, that wasn't lame enough, so they wrote a story where one of her triplicates died when these three ordinary girls tried to attack a giant killer robot. Did they just replace her with one the billions of other people who had this same crap power? No, she just changed her name to Duo Damsel and went about her business at 2/3 of the power.