I don't know that those two speedsters are good comparators. Quicksilver and the Scarlet Witch do not really seem to have been created as continually appearing characters. Their function was primarily to be the sympathetic members of the badguy team in a title that, at the time, nobody was yet sure was going to last.
There are definitely examples of non-solo-material characters created in teams (most of the X-Men, as you point out), but there are counter examples as well. The Thing has supported both team-up and multiple solo titles over the years. You also have team characters whose abilities are pretty diverse and complex (like Blackbolt or Cyborg).
Black Canary was created as a solo character. She replaced Johnny Thunder in his feature in Flash Comics in 1947. She's been attached to the JL for so long, it's easy to forget her roots.
I do agree with your point here. Sticking with my examples of Blackbolt and Cyborg, neither has proven to have legs as a solo property over the long-haul.
Wouldn't my Martian manhunter team, be more of an all-star model then a standard team model. All these characters have had solo books at some point. And in the case of Wally he had it for quite some time. Also, I clearly placed them into definite roles.
Martian Manhunter: leader
Green arrow: Lancer
Powergirl: Big guy (metaphorically)
the Atom: smart Guy
Wally West: the heart (When ever they stop trying to destroy the character)
And Vixen in versatile sixth ranger role.
Not really....
I would say there are different factors:
1. Age (some heroes are better when they are teenagers and some better as adults)
2. Supporting cast
3. Storylines
4. Freedom (how big is the city etc.)
5. How the hero is shown
.
.
There are heroes whose first Solo-Run I REALLY REALLY loved while I didnt like their second Solo-Run at all...
I think the writer is much more important. The usually give that kind of books to newcomers and they don't make enough waves. Do you remember that JLU episode where Ollie, Dinah, Huntress and Question hang out? No one really "major" there (keep in mind this was before the CW show). Also, how much attention did Tom King get with The Vision? Anyone who says he's a major character is a blind fanboy.
I totally love when the give C and D list characters to awesome writers and that's pretty much the only way such a thing would work, IMHO.
- We were the BEST, Richard. No matter what anyone thinks. - Damian Wayne.
Green Lantern Spanish Fan Site HERE
That's a necessary, but not sufficient, condition for a solo to succeed, especially with the sort of characters we're talking about. Other needed elements are a writer who cares about the character, and one who understands what makes the character tick, or what could make it tick, and has a plan for the title, complete with a niche for the character, and a middle game, and eventual end point for a run.
Then of course, there's the artist, who should have a style that's suited to the character. For some of the character mentioned, those elements haven't come together yet.
A great example of what you just described was Marvel’s 1997 Ka-Zar book. Andy Kubert’s re-imagining of all the characters and dynamic take on the Savage Land was highly regarded, and Waid’s story had a beginning/middle/end.
Once they left the book it limped along for a few more issues then tanked.
But your formula DID work.