Cup is a conestant on Object Madness
Cup is generally described as reckless and vengeful. Despite her faults, she cares for her friends, such as when she stood up for Puffball when Cherry was yelling at her.
She is shown to be determined when she was racing against Football and kept running until she won for her team.
It is possible that she can be sarcastic at times. An example of this is when Puffball asked her to stop throwing sticks, she said "Oh, I'm sorry. I guess the other team, like, deserves it." in an insincere/unkind tone.
The two aforementioned examples may also suggest or even imply that she is competitive like Cherry, or it may just be a result of her vengeful personality.