In bothe cases, I think the "less successful" situation could make for a good essay IF you can convincingly demonstrate what you learned from the experience. For the situation where you were wrong, you can talk about how you put aside your pride and pursued the other option once you realized that it was the right thing to do. For the time when you were in a bad team, you can talk about what you learned and, ideally, then show how you put these learnings to use in another situation. That last pasrt is what will really make your essay strong, if you have such an experience.
For the situation where you were right and others were wrong, you can write a good essay about how you persuaded others to see your point of view. This is considered a key trait of a good leader. For the high-performing team experience, you can talk about why it was so great, and again, then hopefully talk about how you applied these ideas in later experiences.
MIT is most likely looking for teamwork and leadership traits with these questions, but they're so wide open that you could demonstrate other traits, such as analytical abilities (proving that your idea was good) and creativity. Don't be shy to take the essay in a slightly unconventional direction if you have a good story to tell.
My main piece of advice, though, is to show how you improved on your own performance in later situations using what you learned. Hopefully you will have experiences like this to write about.
Scott
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Co-Author, Your MBA Game Plan