Episodes suggesting a friendship
In "Getting Teardrop to Talk", Barf Bag asks if Spongy will take her seriously, since no one else will. Spongy enthusiastically says that he will, and later on they become teammates. Later, Barf Bag and Bracelety use Spongy as a trampoline in order to get the basket to X.
In "What Do You Think of Roleplay?", she repeatedly asks "Right Spongy?" to who she believes is Spongy.
In "Return of the Rocket Ship", Barf Bag and Spongy appear to have tried unsuccessfully sailing multiple paper planes. She tells Spongy that she's truly supportive of him when Spongy accuses her of thinking he can't sail a plane and later tells Spongy that she isn't ditching him when she leaves to speak with Taco. She pulls Spongy out of the water and after Taco leaves asks if he wants to play table tennis.
In "Why Would You Do This on a Swingset", Barf Bag hops into Spongy's mouth and uses her vomit to propel her team's swing in circles.
In "Return of the Rocket Ship", the two are seen in a pool with multiple paper planes that Spongy attempted to sail. Barf Bag tries to tell act supportive for him while not offending him, but Spongy acts very standoffish and annoyed.
In "Don't Dig Straight Down", Barf Bag gets the idea to use Spongy's body on a steep hill to get the entire team away from the rising lava and then tries pulling him up with her team to no avail.
Episodes suggesting a conflict
In "What Do You Think of Roleplay?", after their team loses, Spongy gets upset that nobody noticed that he was gone. He questions if they even know anything about him, and Barf Bag tries to tell him that they do, but he tells her that they don't.
In "Don't Dig Straight Down", Spongy abandons his team, including Barf Bag, because they forgot him in "What Do You Think of Roleplay?". He does, however, seem to be slightly guilty about it at first. Barf Bag seems especially upset by this. When she and Gelatin make it to the top, she sarcastically thanks Spongy for giving them a ride.