The first two of these trailers are anime-style introductions to the world and characters of the new game. Notably, the voice of the Pikachu in these trailers is not played by Ikue Otani, but rather by Rie Kugimiya, a Japanese voice actress synonymous with Tsundere characters. This Pikachu also has an interesting cosmetic difference, in having a notch on its tail similar to the top of a heart shape which makes it a female Pikachu.
The third trailer shows two siblings going on different Pokémon Journeys with the new Magnagate feature, taking advantage of the 3DS's AR functions. While the two children change into different Pokémon each time they enter the Magnagate, though this is most likely intended to represent simply the range of Pokémon that players might end up becoming, rather than to demonstrate an actual gameplay change from previous Mysterious Dungeon titles.