Splatoon REALLY needs a team of at least four for the ink mechanic to work, plus I think it'd be a cool mechanic for other teams to basically be able to track you based on what color you're shooting. Kind of discourages just laying down on the trigger
As for the Smash Bros idea, it SOUNDS cool, but that's not Battle Royale, that's more like king-of-the-hill (which is really cool too!). Battle Royale kind of implies that you get nothing going in and have to pick up weapons on the way to tracking down your opponents; in Smash, yes, there are items, but you can't retain them, and you can already see where everyone is on the screen