Princess Peach now has a highly complex emotional system, where she starts off nervous and innocent, and slowly becomes more comfortable, happy, until finally she becomes cruel and taunting. Throughout these different stages, she also has a nuanced range of sub emotions that change depending on her situation, or in reaction to what bowser or the Chatroom say to her.
As well as that, Peach and Bowser can also talk to each other now with voice clips. What they say changes with context of course, and they can have conversations or react to one another.
Peach can also talk to the chat, or talk to Mario watching the video.