They're two separate **bleep** games. It's not like the Sojourners inclusion would affect the game Journey, which is how most of you seem to stupidly think.
@IzoGuy Yes and no, it's not so much the Journeyer being included ruins the character it's more so how theyed go about it. PaRappa, Fat Princess and Sackboy aren't fighters in the slightest but thanks to the setup for their games and such it's very easy to make cartoony or funny fighting styles out of their character or by using items and other characters from their game but Journey shares none of these traits and has nothing to work with.
Phoenix Wright in Marvel vs Capcom isn't a fighter either but his game is very comedic with a lot of iconic ways to make a fighting style out of him even as a joke but Journey doesn't, it's just floating around in a desert solving puzzles with no threats and no items for which the Journeyer can even use as tools. So trying to make the joke fighting style would be the only option for the Journeyer BUT it's making a joke out of it that would make it feel forced and out of place.
Square could be scarf attacks
Triangle could be floaty kicks
Circle could be the song action
And what you say makes no sense. How they go about it.. They would go about it like they do with any other character.
The Sojourner would be an awesome character and would not in any way "ruin" the game's image, since the actual game is not connected to All-Stars.
At least the other non fighters in the game retain a lot of what made them popular as a character and for their game. It's a bit like if they took Gordan Freeman from Half Life or Chell from Portal and put them in a fighting game, both those characters are blank slates and it's upto the player what mind set those people had so giving them generic fighting moves and taunts to try and mimic other fighters will contrast with so many peoples idea of how that character actually thinks and acts.