Disney vs Warner Bros
Connection:
Both are cartoon anthropomorphic ducks created by rivaling companies (Disney and Warner Bros respectively) who are second fiddle or supporting characters to very famous cartoon characters (Mickey Mouse and Bugs Bunny respectively), something which they envy and despise for. Despite this, they are considered best friends and help them
Both possess toon force which enables them to tank everything that happens to them
Both are known for their terrible luck and are easily short tempered
Both have anthropomorphic duck girlfriends (Daisy Duck for Donald and Melissa Duck/Tina Russo for Daffy)
Both also have a catchphrase they use if they're angry or disappointed (Donald's "Aw phooey!" and Daffy's "You're despicable!")
Both have actually fought in the movie Who Framed Roger Rabbit
