What are the main Characteristics of Shakesperean Comedies? Do they have any influence from Plautus or other classic writers?
Shakespeare was influenced by many classical writers including Plautus. Most notably, he borrowed the mistaken twins idea which he used in both The Comedy of Errors and Twelfth Night from Plautus and his The Twin Menaechmi.
He was also influenced by the social and political satire of Aristophanes in the so call problem comedies, for example Measure for Measure and The Merchant of Venice.
It must be remembered that term comedy is used in the classical definition. The situation goes from bad to good.
Another important influence in his writing was his knowledge of the actors he was writing for and their skills. For example, when Will Kemp was the leading comic actor, the fool characters tended to be clowns and buffoons as exemplified by the characters of Bottom and Dogberry. When Kemp left, he sold his share in the company to Robert Armin. As a result, we have a more thoughtful and witty fool like Feste.
Shakespeare was also influenced by folk lore and his contemporary observations of the world he lived in for material. He took in all this varied information and synthesized it. The results are comedies ranging from the silly and farcical Comedy of Errors of twins and mistaken identity to the fantastical A Midsummer Night's Dream to the darker and more serious social and political commentaries like Measure for Measure.
Thus it can be seen that there was not just one influence or characteristic to his comedies but many. His genius covered the full range and was influenced by numerous writers and circumstances.