Cyrus's introduction in Celestic Town. To demonstrate the control he plans to have over time, he takes out a pocket watch as he talks. As his speech goes on, we notice the glass start to crack. Finally, as he proclaims that he intends to become a God, he BREAKS THE POCKET WATCH IN HIS BARE FIST.
Hareta flinging his shoes and socks off and declaring to Mitsumi and Team Galactic that they're fighting him too.
Jun, who up until that point had been ineffective comic relief, blasting out of the exploding Team Galactic base on a Dragonite with Mitsumi (who had been given up for dead a chapter ago) and Hareta in tow.
Everyone, including the main characters, the Gym Leaders, and Team Galactic, joining forces to force Dialga and Palkia back to their own dimension.
Everyone joins forces again to stop Giratina at the end of the next arc.
This one is part Berserk Button, but it still has to be mentioned. Hareta broke out of Charon's rope when Charon said he sells Pokémon. And within a few seconds, after the Jerk Ass Koya was going to arrest Mars (who Hareta knew had changed for the better), he FLOODS THE ENTIRE CAVERN FOLLOWING IT BY THROWING CHARON 20 FEET ACROSS THE CAVERN!
Really, Hareta in and of himself is just one walking Crowning Moment of Awesome (or Funny, or both).