The idea is ridiculous. They need to introduce at least half of them before they team up. In case you aren't aware, the Hobgoblin and Harry Osborn didn't get along. They aren't going to be on the same team. Personally, if it was done properly, I would love to see a Sinister Six movie (with Kraven the Hunter, not Harry Osborn), but for the second Spider-Man movie? That doesn't make the slightest bit of sense. Spider-Man has encountered exactly one super-villain in the movies so far, and he's dead. Where do six vengeful metahumans come from that?
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I'm the best there is at what I do, but what I do isn't very nice.
Spider-Man can't take on the entire Sinister Six simultaneously. He's incredible, but he only survives huge battles like this when the Six are divided. This is when they are fighting among themselves, or if they take turns like morons, or when Spidey gets the drop on a few of them and incapacitates part of the group. In a group melee, Spider-Man usually will try to lead them into collisions and other ways one villain can knock out another one. All at once, Spider-Man would be hard-pressed to win. This is considering that the repeating members of the Sinister Six (that haven't come back from the dead recently) are Doctor Octopus, Electro, the Vulture, and the Sandman. Add in a new Kravinov or Venom, and Spider-Man has to count on them taking each other out or coming at him one and a time.
And this is not going to be a friggin' movie. Possibly an animated one, but don't hold your breath. Marvel isn't in the business of catering to the fans much anymore.
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I'm the best there is at what I do, but what I do isn't very nice.