King Boo vs. Giratina

Introduction
Papyrus: ''Ghosts. You know 'em, you love 'em, and they come in many shapes and sizes, but are usually classified as spirits of the dead, and come in many different types.''

Sans: Some are completely sweet and kind beings, while others are bone-chilling creatures that would kill you where you stand, but these two ghosts come from very popular video game franchises.

Papyrus: ''Nyeh heh heh! They are some of my favorite ghosts, too. Like King Boo, the great ghost that had bothered Luigi during Luigi's Mansion!''

Sans: '''And then there's Giratina: the Renegade Pokémon. I'm Sans, and Papyrus is my bro, and we are here to analyze the characters and see who will win a Death Battle.'''

King Boo
Sans: So, King Boo.

Papyrus: ''I remember first playing that game! In the game: Luigi's Mansion, Luigi seemingly won a huge mansion that wasn't there before. Huh, strange when it comes to retail. That is, if it weren't for all the ghosts filling the place up.''

Sans: '''Yep, that's right. And who can we thank for that for none other than the big bad of the game himself: King Boo. Appearance-wise, in general, he is just this giant Boo wearing a crown, but in the Luigi's Mansion subseries, he had a dark shadow over his eyes as well as a jewel on his crown.'''

Papyrus: ''King Boo is at a Multi-Universe Level attack potency, because the mansion that he created had five separate universes in it. The game's manual even says so.''

Sans: '''But aside from that, King Boo has some amazing feats. Like many ghosts, he is presumably an undead spirit who might have or might have not have been alive at some point in time, we never really know about his past. He can shoot fireballs and suck them back up, and can create entire UNIVERSES from nothing. Like the common ghosts, he can levitate, teleport, and all that stuff, but to a greater extent.'''

Papyrus: ''And, King Boo's crown contains a powerful stone, that allowed him to break a mysterious crystal known as the Dark Moon, said crown can generate electricity, and a whole number of things on the boot. But, aside from that, even the King of the Boos himself has his fare share of weaknesses.''

Sans: '''King Boo is very arrogant, and some say that his power revolves around the number of Boos that follow him. And yes, he can still be harmed physically, blinded by bright lights, and he can even die if the right buttons are pushed. But even then, he is still a force that even Mario had a hard time dealing with.'''

King Boo: I don't plan to give up my favorite decoration. I like Mario where he is.

Giratina
Papyrus: ''And now we come to the world of Pokémon. This strange world is full of strange creatures that are known as Pokémon. They tend to represent plants and animals, and some even go through certain stages of 'evolution' in which they grow into a stronger form.''

Sans: '''Yeah, that's right. But some of these Pokémon hold dominion over various concepts such as dreams, truth, ideals, life, death, and the works. Three of them even have power over time and space as a whole. The Creation Trio was made by Arceus to shape the multiverse, which consists of many branching timelines, like ones with or without something known as Mega Evolution.'''

Papyrus: ''Dialga controls time, Palkia controls space, and Giratina is the third one. His dominion is mainly unknown, but many think he is the embodiment of antimatter. He was supposedly banished for his violence, and is commonly thought of as the devil, but he has proven that he's not the devil, as he dragged Cyrus into the distortion world, and Ash even befriended him!''

Sans: '''In a sense, he keeps balance. Giratina is a Multiverse Level+ titan that embodies the antimatter of the Pokémon Multiverse, and he is one of the most powerful of his kind that you can find. He is a Ghost/Dragon-type Legendary Pokémon and the third member of the Creation Trio, along with Palkia and Dialga. He has two forms: his altered form and his origin form.'''

Papyrus: ''His Altered Form is the form he appeared in Diamond and Pearl, and this is the form he commonly uses when in the overworld. His Origin Form appears in areas where there is a lack of gravity, such as outer space, but he could also be in it when holding a special stone called the Griseous Orb, which boosts his Dragon and Ghost-type attacks.''

Sans: '''Giratina is also capable of handling his own with Dialga and Palkia, and could even fight on his own against Arceus, even if it is with the help of Dialga and Palkia while doing so, but even then, he does have his weaknesses. While powerful, he is vulnerable to Dragon, Ghost, Dark, Ice, and Fairy-type attacks, and his Origin Form cannot appear in a gravity-based environment without the Griseous Orb. But even with those faults, he is arguably a very powerful being.'''

(Giratina lets out its signature cry.)

Death Battle
Papyrus: ''Nyeh heh heh! This is going to be good.''

Sans: '''You can even say this is a GHOST of a chance to see in your universe, which it is fortunate enough that we aren't in right now. Anyway, it's time for a DEATH BATTLE!'''