Introductions, people! This thread's about introductions!
Well I've posted my preferred introduction to the film in general with-
Black Screen - White text fades in and is read aloud by Nick Fury:
"And there came a day, a day unlike any other, when Earth's mightiest heroes and heroines found themselves united against a common threat. On that day, the Avengers were born to fight the foes no single super hero could withstand! Through the years, their roster has prospered, changing many times, but their glory has never been denied! Heed the call, then for now, the Avengers Assemble!"
Kick in the epic music - Opening Title Sequence as Captain America goes through the unfreezing process at SHIELD
NICK FURY
Welcome back. Somebody get Stark on the phone.
Iron Man Introduction
Cut to Stark doing something inevitably over-the-top and ostentatious just for the sake of doing something over-the-top and ostentatious like an enormous party in Dubai or some ****, surrounded by women and celebrities. He gets the call from Fury and tries to wave him off, not interested in talking to a frozen guy at the moment.
STARK
I don't know if you heard but I'm a little busy right now. What is it you wanted?
FURY
I said get down he-
STARK
Whoop! I'm driving through a tunnel! >hangs up<
Thor Introduction
This is harder to come up with, considering the solo movie isn't out yet, but a cool intro could involve something about them needing an extraordinary force to help take down the Hulk as their first task, then Thor just blasts in as Iron Man, Cap and Widow are bombing and helps them get an advantage. (Later in this scene Iron Man could get screwed by Hulk and Cap will finally take him down, leading Stark to realize Rogers is the best man for the leader of the team as part of a subplot/theme about power struggle within the unit)
Banner Introduction
Not sure whether Banner should come before or after Hulk's appearance, but it'd be cool to start with Hulk doing some parkour **** for whatever reason through Canada and all of a sudden he loses it and starts tearing apart a small town. At this point unknown to both the characters and the audience, he is being controlled by Loki. Banner could appear after the team defeats Hulk and is being held in a cell. In his first scene they go to talk to him, and he explains that he thought he had control over the Hulk until he felt some bizarre force come over him and had him snap. And he's sure it wasn't Hulk.
For Fury, Widow, and Hawkeye, they could all just be chilling at the SHIELD base and have a casual introduction. For Pym cameos, I think if they really need some scientists working at SHIELD to supply the team with anything, then they're perfect for the job. But otherwise, just cramming them in for fan service is a no-go.