Coffee

Coffee at first glance seems to be the average smart character in your object show, from being generally pretty bossy to having her own lab. However, she seems to have more to her than she wants to let on.

Coffee is shown to be pretty passive aggressive and doesn't seem to have much regard for the safety of others if its what she has to do to win. She holds grudges, going as far to punch a fridge after Cakey ruined the challenge for her in "ONE-SHOT WONDER". She also prides herself on her intelligence and seems to judge others based on that quality as well, disliking Slingshot and Grapefruit for their simple-minded nature and seeing the latter as a liability.

Beyond that, Coffee's intentions might go deeper than just wanting to win the competition, seemingly having created Phone and rewarding him for being more hostile, not even necessarily because it helps her win. However, behind all of this, she might actually have good intentions, genuinely wanting to strike a friendship with Cakey (though she could very well have just wanted to form an alliance to get ahead in the game).