Greta

Britta is a monster who one day is playing a game of wubba ball in the park with her fellow blue monster friends when Elmo comes along and asks if he can play. She refuses to let him join in, saying only blue monsters are allowed, but Lila doesn't think fur color should make any difference, and since the wubba ball is hers, she insists that Elmo should be allowed in the game. The other monsters agreed and invite to Elmo to join in.