Swords dance is a move in Pokemon where your opponent does no damage, but doubles their attack power, allowing them to deal twice as much damage every subsequent turn so long as that Pokemon stays in the battle. A small decrease in damage dealt now in exchange for more damage dealt later.

Most children play Pokemon with a simple goal to attack every turn, and don't pay attention to what non-attacking moves do. They view all such moves as a waste of a turn, represented by the bored spongebob. Adults playing Pokemon better understand strategy, and realize that the opponent becomes much more threatening after using swords dance.

Swords dance is a move that doesn't do damage but makes the pokemon deal attack double. Most of the time as a young pokemon player you'd disregard these kinds of setup moves as you'd just cram 4 attacking moves on everyone.

On competitive pokemon getting set up on is very dangerous and could lead to you losing the whole fight.