I agree, Prankster Comet is probably Rosie's final smash. IDK why I didn't come up with that.
Also, Mic-128, Lucario did in fact replace Mewtwo. There are several examples of incriminating evidence. For example, in the first few frames of Lucario's dash, it appears that he is floating. As well, Aura Sphere is very similar in function. Both their side specials are specialized grabs. Neither of their up specials deal damage. Both their forward smashes involve blasts of their respective elements. Both of their sub-100% ledge attacks involve flipping. There is absolutely no evidence that they were both supposed to be in the game. On the other hand, why would Nintendo copy Mewtwo's dash if they're just going to completely change the animation? Because: Lucario went over Mewtwo. Also, IDK if it's just me, but Lucario's voice bear a passing resemblance to Mewtwo's. Also, Lucario TELEPORTS onto stage. Why would that happen, hmmm. Mewtwo teleports but not Lucario. As well, Lucario slowly floats down onto stage. Wait, WHAT!!? Floats, but Lucario doesn't do that, but who does? MEWTWO. Why in all creation would Nintendo copy so many of Mewtwo's aspects onto Lucario, especially with all the de-cloning stuff going on in Brawl. The only two that are even remotely similar are Link and Toon Link. And, to back that up, they ARE the same person. I can think of a zillion moves to give Lucario instead of Aura Sphere, close combat just to name one. Why so many similarities? Lucario is essentially a re-skinned Mewtwo, done at the last stages of development. There is now proof that they were intended to be together, but there is evidence they weren't. Also, Lucario's forward smash could have been a back hand punch similar to Wolf's. They're up smash animations are similar, too. It also seems likely that Mewtwo was going to be buffed from Melee to Brawl, and Mewtwo's Brawl down smash likely was intended to hit on both sides, acting as a double shadow bomb with less damage and knockback, hence explaining Lucario's down smash facing the screen. The reason Lucario was a last minute re-skin? Mewtwo is a Gen-1 Pokémon, and Nintendo, in act of outrageous stupidity, thought that meant he was irrelevant. Now, this didn't come to light until they realized how popular Lucario was. Seeing an opportunity to advertise Gen-4 and make people happy, they stupidly made a brash decision to replace Mewtwo with Lucario, thinking it would please people. Simply put- it didn't. That explains why Mewtwo was the ONLY non-clone not return from Melee. I mean, if Nintendo was thinking, they should have kept Mewtwo as a Pokémon and gave Pokémon trainer the Gen-4 starters. But Nintendo thought that the Gen-1 starters, of which the only truly iconic one was Charizard, would be a better Gen-1 representative than the ever-popular-more-so-than-Charizard Mewtwo. Why not put in the Gen-4 starters? They sucked, to be honest, and they weren't exactly fighting-material. So, they couldn't put Lucario with Pokémon Trainer, so they made a separate character, thinking they had found the perfect solution. Well, it didn't. One way they could have addressed this problem, put in the Gen-4 starters. They are not exactly fighting material, but with hard work, you can make them one, kind of like Rosalina. That also may have boosted Gen-4's popularity, considering them being fighters and all. Lucario may have been popular, but not even as close as Mewtwo. Besides, another way, PUT THEM BOTH IN!!!!!!! IT'S NOT THAT FREAKIN' HARD!!! But, that didn't happen. They didn't want to over-represent Gen-1, so they removed one of the most iconic Pokémon ever for advertising purposes. Classic real-world. There you have it. As you can see I'm very passionate about this subject. Lucario would be the first person I'd remove from the Smash roster, if necessary. Also, now that Nintendo has seen the backlash and Mewtwo is getting all this attention, what the movie and Megalutions, he has about a 95% chance of making it, hopefully as regular Mewtwo. Though, that may not be likely. I swear I just want regular Mewtwo. They could them in as Final Smashes or whatever, but PLEASE not a Megalution as his basic form. Not even Mega Mewtwo Z, which is bound to happen, could possibly replace Mewtwo, except he could included as MAYBE a Final Smash, though I'd rather have ANY move as his Final Smash than either of those 3, even just splash.