Can't believe mods are already here. I also can't believe they're allowed in tournaments. Are we really sure these costume patches don't alter moves or hurtboxes? Even just a little?
Sick Beefy Smash Doods combos though.
Costume mods shouldn't affect gameplay, as they by their nature don't alter hitboxes or animations (even if the size of the costume model doesn't quite match up with the character's hitboxes). The slightest difference in the size of a hitbox, a move's damage, or anything would also cause a disconnect online, which further proves that gameplay is unaffected by these skins. The only way that gameplay would be affected by a costume mod, would be if the bones and rigging didn't match up. For example, since R.O.B. doesn't have things like legs, putting him over a character with kicking attacks can cause hitboxes to glitch out and stretch across the entire screen.
It should be pretty easy to check whether or not a mod affects gameplay. Each character has separate folders for skins, and for their scripts (coding, move properties, etc) / animations. TOs would just have to look through the SD card using a computer, and check that those folders are not modified by the mod. Folders that aren't changed by the mod aren't included on the SD card, so searching the card – using something like Windows Explorer's search function – for folders with those names can be done to ensure that the mod does not affect gameplay.
Their just kickass costumes that makes them look so much better than they already are, it's just a new look not anything drastic to their moveset this isn't Project M 2.0 you know. With that being said, I would not be surprised at all if they sneak in any Akuma, Mr.L, dark Bowser, hell even Sora costumes in this mod, where can I get one???
Right now, the hotspot for Smash 4 mods is
Gamebanana. You can either download individual mods and make your own custom build, which requires a game dump, or you can download a pre-made modpack that's ready to go right out of the box.