Like Smash 4, when a new character is shown, there's a trailer with him, to show his abilities and fighting skills.
E3 20XX: Devastation is near
A stork with Baby Mario and Baby Luigi is flying to give some letters to some characters. Baby Luigi drops a letter and a pink, round robot gets it. It open the letter and, happily, jumps and runs: SUKAPON RETURNS IN THE BRAWL! Then are shown some characters: Mario, DK, Link, Pikachu, Olimar, Pit, Fox, Samus, Villager and Little Mac. There are some gameplay sequences then Mario and Bowser are fighting in Battlefield and Mario defeats his opponent when Sukapon appears. Then, there's a sequence with Sukapon's gameplay and all the characters run into a black hole: the title of the game, Super Smash Bros. Devastation, is formalized by the announcer.
E3 20XX (second day): Power of nature
Mario, Sukapon, DK and Link are fighting when a boy appears. Link throws to him his Boomerang but the boy creates a giant green hand and deflects it, than he shows who is: MATTHEW USES THE PSYENERGY! There is a section which shows each of Matthew's special move (in the order): Move, Helm Splitter, Bramble, Haunt, Gaia, Ragnarok, Demon Knight, Cure, Flame, Annihilation, Spire, Thunder and Judgement. At the end Matthew points his sword backward and a female voice says: "Surprised to see me in Matt?"
E3 20XX (third day): Nintendo Land
Mario, Pit, Little Mac and Matthew are in Nintendo Land. They are amazed and when they see Monita, she just hits them with a Mii dressed as Pikmin: MONITA EXPLAINS HOW TO FIGHT! Then there's a brief clip with Monita's moves. This is the shortest trailer released.
The last castle
This trailer starts with a gameplay from Super Mario Bros.: Mario has defeated Bowser in the world 1-4 and comes to the Princess but appears a Toad which says: "Thank you Mario, but our Princess is in another castle!" so Mario throws a fireball to him. Then the trailer's style returns normal and Toad appears angry: TOAD ISN'T IN ANOTHER CASTLE. Starts a sequence of Toad's abilities and, at the end of the video, the graphic's style returns to Super Mario Bros.' and Toad defeats Bowser in world 8-4 and saves the Princess.
Kirby is fighting Marth and Toad and they are all using the Paint Shooter item. They are very inaccurate as they miss each other. Suddenly, three ink shoots hit Kirby, Marth and Toad and from the top of a wall appears an orange squid girl: INKLING DIRTIES THE COMPETITION! A sequence which shows Inkling's abilities starts and at the end, when Marth tries to shoot to her, the Inkling shoots to his face a big ink ball.