Petal Dance makes you confused.
This is probably the entire reason they put Psyduck into the Petal Dance group. It's a joke: the others are just enjoying some dancing, but psyduck, the pokemon who is constantly confused and suffering from migranes, also gets it. Yes it makes EVERYONE confused at the end, but i'd really put forward the joke of confusion is why Psyduck specifically got it.
This is probably the entire reason they put Psyduck into the Petal Dance group. It's a joke: the others are just enjoying some dancing, but psyduck, the pokemon who is constantly confused and suffering from migranes, also gets it. Yes it makes EVERYONE confused at the end, but i'd really put forward the joke of confusion is why Psyduck specifically got it.