The first 13

The premier should have more characters than the original game had, but not too many. I think Mario, Link, Kirby, and Pikachu all need to be in the first 4 showed. Similar to Brawl, they start fighting

Samus should quickly appear of course with her bombs and lasers.

Fox would also appear using his blaster.

Ridley would come from the sky. He starts to attack everyone except Samus.

Starfy comes to the aid of Kirby and shows a fighting stance against Ridley. Ridley taunts and Starfy unleashes a final smash on him.

Geno should start by coming to Mario's aid. Showing off a few of his moves as well.

Little Mac should appear next to Link's help. He'd show a variety of punches on Pikachu.

Lastly, Mewtwo should appear to aid Pikachu. He'd enter by shooting down Little Mac with his shadow balls.

Megaman should be last for the surprise of course. This would really top off the trailer.

Mewtwo

First Appearance
Pokemon Red and Blue
1998 
Mewtwo is the star of the first pokemon movie, the highest level legendary pokemon, and the "king" of the Kanto region. He's technically a veteran, but didn't appear in Brawl. Most fans don't know that he was planned on being in Brawl, though. Hackers found a file for his victory theme and a final smash sound effect. It's even rumored that the "random character" space in Brawl was supposed to be Mewtwo's space.

For obvious reasons, most fans believe that Lucario "replaced" Mewtwo. This however, is obviously not true. The only move they share in any way is their standard "b" move. Other than that, they have no similar moves. For this reason, I don't believe Mewtwo should have any moveset changes in the next Smash Bros. game.

Until Pokemon Black and White came out in March, I was unsure what Mewtwo's final smash could be. But little did I know that GameFreak could help with that situation. Mewtwo gets a new move that he learns at level 100 called Psystrike. Mewtwo is the only pokemon that can learn Psystrike, plus it's a powerful move. This in my opinion is an obvious choice for his final smash.

Mewtwo would be a great character unveiled at the next E3 because of the hype of the fans. He is a character people all want to see return. Also, people would start speculating all over the internet whether or not other "abandoned" characters would return. Most people don't care about Pichu, Dr. Mario, and Young Link (all of which I will talk about in the future), but Roy is another character people loved who was not a direct clone. This move of putting Mewtwo in the first trailer could make or break the Smash Bros. game the spotlight of the next E3.

So PLEASE Nintendo and Sakurai, do the right thing and bring back Mewtwo. Also, if you'd make him a little faster, that'd be great, too.