Any time you pull off a Super Strike, and even more so if you make it a "perfect" super strike.
The opening has Mario score a goal by kicking the ball hard enough for it to set on fire and push the Kritter goalie to the back of the net. Every character can do this as long as you make a "perfect" Super Strike.
In general, just how emotive the characters are in this game. This is probably the only Mario spin-off that doesn't use the same familiar voice quips that longtime fans are used to hearing, plus everyone shows off how expressive they can be if they were allowed to show more than the bare minimum of their personality in a non-RPG Mario title.