Draco in Leather Pants: Zero's one of the few movie antagonists to get much in the way of a sympathetic backstory, but some fans use it as an excuse for all his actions, up to and including attempting to destroy the world from the Reverse World.
Ensemble Darkhorse: Many fans agree that Regigigas has one of the best scenes in the movie.
Fashion-Victim Villain: No-one would hold it against you if, upon looking at Zero's design and that of his ridiculous jumpsuit, you thought it was someone's Giratina gijinka fanart ripped from DeviantArt.
Foe Yay: There was something going on between Zero and Newton Graceland. After Zero's early Face–Heel Turn, there is considerable Foe Yay between the two
Hilarious in Hindsight: After accusations from Moral Guardians that Pokemon encourages children to worship the devil, there's some irony to be had in Ash and friends befriending the Pokemon equivalent to Satan.
Narm: Just about everything related to Zero. His speech is really off, and a lot of it is because he emphasises and stretches random words and syllables. And his ridiculous jumpsuit makes it impossible to take him seriously even when the movie wants you to.
Do not piss off Giratina, for it will stalk you... and then drag you into its twisted screwed up world and try to kill you.
In the manga version, it is implied that Zero dies when the Mecha Giratina is frozen in the glacier; becomes kind of a Tear Jerker when you realized Newton has disappeared after Ash returns from the reverse world...
The pictures of the town getting crushed by the glacier.
The Scrappy: Shaymin acts like a bratty, self-entitled jerkass, particularly to Ash and never gets called out on it. Even worse, when Ash understandably objects to this treatment, the others turn on him and act like he's the asshole. And worst of all, Shaymin doesn't really do much to earn his mention in the movie's title, spending most of the film acting incredibly smug, demanding complete strangers to be his taxi service, begging people for food, and generally being an Ungrateful Bastard. Ironic for a character described as the "Gratitude Pokemon". The only thing of importance he does is save the life of the real star, Giratina, so that he can go finish off the villain.