Here's what I would do:
Promotion
This is where I think Nintendo messed up. I would promote the living CENSORED out of a sequel.
Characters
I would keep all of the agents from EBA1, and (obviously) have new people to help.
Songs
"Livin' la Vida Loca" by Ricky Martin (Wasn't this supposed to be in the first EBA?)
"Rope" by Foo Fighters
"Don't Stop me Now" by Queen (with Phoenix Wright story)
Promotion
This is where I think Nintendo messed up. I would promote the living CENSORED out of a sequel.
Characters
I would keep all of the agents from EBA1, and (obviously) have new people to help.
Songs
"Livin' la Vida Loca" by Ricky Martin (Wasn't this supposed to be in the first EBA?)
"Rope" by Foo Fighters
"Don't Stop me Now" by Queen (with Phoenix Wright story)