SCE Santa Monica: Because they get shit done. They also have collaborated with numerous other studios in the past with success.
Eighting: They have successfully developed/co-developed countless popular fighting games.
Q Entertainment: Their planning, experience, and unique talents towards game design.
Importantly, Eighting and Q Entertainment worked together in the past and helped develop a certain fighting game called Battle Stadium D.O.N.
What Project Super Smash Bros/Power Stone based game. The companies would be tasked with making a Battle Stadium D.O.N. sequel with PlayStation characters added to the mix. What is Battle Stadium D.O.N? Its Super Smash Bros but it pitted characters from Dragon Ball Z, One Piece, and Naruto against each other instead of Nintendo regulars.
Of course its already rumored Sony is working on such a title named "PlayStation All-Stars Battle Royale."
If you haven't played Battle Stadium D.O.N. it might be because it never came to the west. The game had a Japanese only release on PS2 and GameCube because of licensing issues. But with the popularity/profitability of Smash Bros. and One Piece games I think something can be worked out.
Pitting PlayStation All-Stars against some of the top manga/anime stars isn't hard to design. Licensing is hard. So incomes the backup team and make the same game...only replace D.O.N. with Capcom characters.
At any rate I hope there is some sort of collaboration and the possible upcoming PlayStation All-Stars is a AAA knock-out.