What functions in the plot do Puck and Bottom serve?

Both Bottom and Puck are considered "comic fools". Puck is more a traditional sort of fool entertaining Oberon. Bottom has a more contemporary wit to him. He sees the world in his unique way yet his humorous musings have truth to them. Both these "fools" serve practical functions in the play. They not only further the plot but add thematic meaning as well. While bottom has good advice, as in how to stage the play Pyramus and Thisby, he is at a loss how to actually use it. Puck is very much a servant of Oberon as much as a comic. Puck does Oberon's bidding while making astute observations about life and people.