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.
Mario Strikers Charged
The opening cinematic full stop. Perfectly gives an idea of what youre in for. This is how the Mushroom Kingdom does soccer. And its backed up by the absolutely metal sudden death theme!
The fact that due to the arena walls being electrified, players enter by jumping down from a lightning airship generating the storm!
Special mention goes to the Kritter acting as the goalie in these situations. Normally, he remains mostly out of the player's control, but when faced with the odds before him, he simply squares up, letting you control him to block the Mega Shots. And as a result, all of the above-mentioned displays of power? The Kritter can block all of it.
The Home entrances consist of the characters free falling from about the same heights they're capable of jumping to and landing flawlessly (except Wario) into an Ass Kicking Pose.
Even Wario's is pretty awesome. There's something to be said about a man who lands on his face and just keeps on going like it's nothing. Especially if he does it on purpose.