Golf Ball and Snowball have shown a major conflict throughout BFDI. Snowball hates Golf Ball due to her insulting him and his intelligence.
Episodes suggesting a conflict
In Take the Plunge: Part 2, Golf Ball told Snowball that his brain is small and Snowball pushed Golf Ball off a cliff and into the water.
In Bridge Crossing, Snowball rememberd what happened in Take the Plunge: Part 2, and rages, catches her and throws her off the bridge. Golf Ball sunk, possibly killing her.
In Power of Three, when Golf Ball is chosen to be on his team, Snowball screams "NO!" for quite some time and continue to fight throughout the episode.
In Puzzling Mysteries, when Golf Ball says she's spinning seven basketballs, Snowball asks her "You think anyone cares?". Later, you can see Snowball chasing Golf Ball when everyone is screaming in the room. When the puzzle was about to be finished, Snowball steals Golf Ball's jigsaw so he could finish the puzzle instead of her.
In Getting Teardrop to Talk, when 8-ball suggest that Tennis Ball, Snowball and Golf Ball should join his team since they're balls too, Snowball refuses due to Golf Ball and the rest of the team being armless.