I really doubt they even know about Digimon Rumble, and it's not a copy of the game, just a little similar; it sure as heck looks way better than Digimon Rumble Arena 2, that's for sure. I'm watching gameplay videos of Rumble 2 and the voices are more annoying than Sora constantly yelling YAH-HWAH-MAH in Kingdom Hearts 1&2, plus I'm sure the game had a much smaller budget and lower developer pedigree. I wish people would stop obsessing about All-Stars supposedly copying stuff, it's taken some cues from other series but it's doing its own thing. It's definitely shaping up to be my game of the year, I can't wait.
Meh, I've played through a bit of all-stars and it really does use Smash Bros as a template. Granted, it's not exactly the same game and formula, but you might as well call it out for what it is; the game is a Smash Bros clone.
Because of the stiff movements, and the animations, and move inputs it's way more like rumble arena. BUT rumble Arena was based of the Super smash bros. series. I feel like the 4 player is fun but agree with many others it can be difficult to track your character.The stages are very nice, and interactive. Throws feel over powered. Since they drain your opponents bar so much and you can drain that into yourself. Overall it's very fun and has it's unique quirkiness but I think it is a bit unfinished or under-polished. Dunno if that is due to a low budget, or lack of experience on the developers side for this genre or something. The Similarities to Rumble arena 2 are more regrettable and only digimon fans remember that forgettable game lol.