Since the beginning of BFDI, Match and Pencil have shown nothing but hatred towards Spongy at every opportunity because of how fat, smelly, and gross he is. They even have a game dedicated to their hate for him. This would at least change with Match in BFB. Spongy himself usually acts like he doesn't care when they insult him or ignores them.
Episodes suggesting a conflict
In "Barriers and Pitfalls", Match says that Spongy just makes her want to hurl.
In "Are You Smarter Than a Snowball?", Match and Pencil play Spongy Cake with mini versions of themselves. Pencil also wrote "Spongy is fat" in her doodle.
In "Crybaby!", they try to play Spongy Cake with a mini Snowball.
When Spongy rejoins the game in "Half a Loaf Is Better Than None", Pencil, Bubble, and Ice Cube walk away from him, disgusted.
In "Rescission", Spongy randomly falls onto Pencil.
In "Get Digging", Match and Pencil are happy to hear that Evil Leafy captured Spongy. When Golf Ball calls Match out for this, Match says she's had to deal with Spongy for over 17 million years and that it's a relief to finally see him gone.
In "Zeeky Boogy Doog", Pencil and Match cheer when Fries tells them that he ate Spongy.
In "Get in the Van", when one of Spongy's tears land on Match, she says that was disgusting. Pencil says Spongy better be eliminated because she can't stand him anymore.
In "Getting Teardrop to Talk", Pencil tells Lightning to electrocute Spongy. Pencil and Match cheer when he does so, all while Spongy moans in pain.
In "Enter the Exit", Pencil says "What the Spongy is going on?" to Four, suggesting that Spongy is something horrible to Pencil.
In "The Escape from Four", Pencil and Match are disgusted at the sight of Spongy's body trying to be squeezed into Four. They both decide coming in contact with his body to escape isn't worth it and bail.
In "Puzzling Mysteries", Pencil tells the Announcer that the carrying capacity of the TLC is six. She then says there are six people but Spongy is kinda big.
In "Reveal Novum", Pencil and Spongy are matched up in the staring contest. Spongy loses.
In "Get Digging", Pencil warns the Puffball riders, which includes Spongy, to watch out for a wild Leafy.
Episodes suggesting a friendship
In "Barriers and Pitfalls", Pencil, Match, and Bubble throw Spongy over the wall in the obstacle course since he's on their team.
In "Bowling, Now with Explosions!", Pencil didn't seem to have any problem with doing an April Fools prank with Spongy.
In "Fortunate Ben", Match claims she analyzed her mean-spirited Spongy Cake game and started playing it with him, which Spongy seems happy with.