Sal, I hope you don't mind me using your sig for this thread. Here is what Kaz Hirai humorously had to say about the matter:
"The final boss in PlayStation #AllStars single player is Nintendo's lawyer"
Protip: it's not the real Kaz Hirai
I see the similarities; I see the four franchise characters on screen at once, I see the 2d plane, I realize that the developer was intentionally making a rival to Super Smash Bros, but I don't think copying these ideas means it is disrespectful to Nintendo, it's commonplace.
Typical fighters all have the same basics; one character on each side of the screen or occasionally more for tag battles/combos, health bar at the top, some sort of power meter that builds over time, a time limit to the round in between the health bars, a character select screen of that franchise's popular characters, a training mode, alternate character outfits, an individual 'smash/power move' for each character etc etc.
But why do we not complain that they're all rip-offs of eachother? Because the characters in each one are different, with different movelists, different 'physics' and fighting on different stages, with different music and different art styles. This all applies to PSASBR. The only difference being that very few other companies have attempted a Smash Bros style game so far, and so many see the genre as somehow being property of Nintendo. I think it is a very unfair ruling; one company should not be allowed to own a particular genre of game simply because they are the only ones making them so far.