An important pitch or presentation is no place to wing it. Write down your remarks beforehand and insist that everyone else do the same. Gather to review your spiels, and offer criticism to one another.
One wrong answer, one contradictory viewpoint, one stupid instance of blathering can cost you the whole thing. One person out of step can send everyone else on your team careening off to correct the mistake.
Don’t be phony or stiff. Have three points, memorize them, then just play that back in your own words. Be sure everyone knows your points, and you know theirs. It’s simple not to be stupid.