Who are the round, static, and dynamic characters in Much Ado About Nothing?

A static character is one who does not fundamentally change throughout a text, and a dynamic character is one who does. A round character is one who is complex, perhaps even contradictory, and would take pages to explain, and a flat character is one who is relatively easy to describe, perhaps only taking a few sentences. On one hand, Beatrice and Benedick could be viewed as dynamic because their feelings toward one another change, but, on the other hand, I'm not sure their characters really do undergo significant development. They must be tricked into loving one another, and their pride must be engaged in order for each one to admit their feelings for the other. Ultimately, their pride continues to define them both until the play's end. That being said, I would classify both as round characters; they may be ultimately static, but they are still complicated.

Don Pedro and Claudio, however, become significantly less proud as a result of their being tricked into thinking that Hero has been unfaithful to Claudio and is not virtuous. Neither initially could conceive of possessing such a personal vulnerability or failing, and, by the end, both have been taken down a peg or two and exhibit less arrogance as a result. That being said, I think they are flat characters because they are not particularly complex.

In comedies, most characters are round, stock, static archetypes.  There is the clown, the villain, the overprotective father, the dreamer, etc...

The only dynamic characters in Much Ado About Nothing are Beatrice and Benedick.  They go from hating each other to loving each other, but they have to be tricked to do so.  So, are they really dynamic?  I think so.  Benedick goes from hating women and loving bachelors to defending Hero and Beatrice's honor by challenging Claudio (a bachelor) to a duel to the death.  That's a change.

The other characters are static archetypes, more or less, especially Dogberry, the bumbling constable, and Don John, the archetypal Bastard.  The others (Don Pedro, Leonato, Hero, etc...) change slightly in response to the plot, but not enough to warrant them as dynamic.  Shakespeare wants to the focus of the laughs to be on our main couple for the high comedy (dynamic characters) and on Dogberry for the low comedy (static characters).

Who are the main characters in the movie Much Ado About Nothing?

The 1993 and 2012 film adaptations of William Shakespeare's play, Much Ado About Nothing, feature the same group of main characters. 

First, there are Benedick and Beatrice, who are both very full of themselves, think marriage to be silly, and seemingly hate one another. Then there is the beautiful Hero, cousin of Beatrice and daughter of Leonato. There are also two brothers, Don John (who is a jealous troublemaker) and Don Pedro (who likes to play at matchmaking). Benedick's friend Claudio is also a main character. Other figures in the plot include Margaret and Ursula (Hero's gentlewomen), Borachio and Conrade (Don John's cronies), Dogberry (a bumbling but charismatic constable), and a meddling Friar.

Throughout the course of the play, Don Pedro makes it his task to set up two couples. After successfully making a match of Hero and Claudio, for whom things do not go smoothly, he plays a long-game of making a match out of Benedick and Beatrice.

Who are the character foils in Much Ado About Nothing?

Finding a single foil has always sort of bugged me when a teacher asks for that kind of thing.  The reason is that a foil is a character that shows qualities that are in contrast with the qualities of another character.  The point is to highlight the traits of the other character.  The reason finding a single foil doesn't make sense to me is because by its very definition you need a pair of characters.  If character "B" is a foil to character "A," then logically "A" is a foil to "B."  

So for "Much Ado About Nothing," I'll go over some foil pairs.  I think that Beatrice and Hero are foils to each other.  Beatrice is intelligent, lively, and incredibly witty.  She also is jaded when it comes to love, because she has been divorced.  Hero, on the other hand, is much more quiet and modest.  She is a bit idealized in the play as that standard perfect beauty.  

Claudio and Benedick are also foils to each other.  Claudio is a young, impetuous soldier while Benedick is more of a seasoned aristocrat of a soldier.  Benedick is adamant that he will never fall in love, while Claudio immediately falls in love with Hero.  Benedick is incredibly witty and intelligent, while Claudio simply doesn't display that kind of wit.  Perhaps because of his youth, Claudio is also easily fooled and manipulated as illustrated by Claudio believing anything that Don John says about Hero.  Contrast that with Benedick who stays loyal to Beatrice.