Waluigi can easily be a clone of :wariobrawl:. It isn't hard to visualize. This is especially true since Waluigi has few moves that are unique to him.
Sure Waluigi is skinny and tall and :waribrawlo: is short and "stocky." But that doesn't mean he can't be a clone of :wariobrawl:. It didn't stop :luigibrawl: from being a clone of :mariobrawl:.
That's not even considering that Luigi has quite a few more moves (and potential moves) unique to him than Waluigi.
You don't grasp the big picture. Literally, anything Mario can do, Luigi can do as well, and this is true in the main Mario series as well. Sure, Luigi has never used the F.L.U.D.D., but it isn't illogical that he could use it as easily as his big bro.
Wario and Waluigi on the other hand, cannot copy each other so easily.
Wario has herculean strength that Waluigi lacks and well as a rotund belly and girth that he likes to throw around, and conversely, Waluigi has freakishly long legs that Wario doesn't have.
Also factor in Wario's moveset. Wario's moveset comes from WarioWare. If Wario had a Wario Land inspired moveset instead, then it can be easier to visualize Waluigi copying him.
Wario's Chomp came from a microgame about eating hotdogs. Waluigi using Chomp makes no sense, as Chomp caters to Wario's gluttony trait.
Wario Bike, yes, Waluigi can use the bike, but then again, so could Bowser and Donkey Kong. However, out of those 4, bike riding is a trait that is more associated with Wario than anyone else, due to the WarioWare series, where his bike is his main method of travel.
The Corkscrew, yeah, I can see, since it's a generic move not based on anything really.
As for Wario Waft, you cannot be serious in that Waluigi can clone that. Farts are a part of Wario, with his "love of toilet humor". Waluigi eats eggplants; the anti-fart food. (Ingenious on Nintendo's part or mere coincidence?) But aside from that, Wario's flatulence is featured in WarioWare on more than one occasion. In fact, one of Smooth Moves' microgames is fanning the air that Wario farted in.
And what about a Final Smash, "Waluigi-Man"?
I know what you're going to say. "But :ganonmelee: copied

!"
However, Ganondorf and Captain Falcon are both of the same build, it isn't out of place for the wielder of the Triforce of
Power to punch and kick infused with his energy of dark magic, and Falcon's moves didn't originate from anywhere but Smash, so they aren't technically "exclusive" to him.
Also, how many times do I have to list abilities Waluigi has that no other character has? I mean, other than F.L.U.D.D., Mario doesn't use any techniques that are unique to him in Smash. Luigi used Capes in SMW. Luigi and Toads use fireballs. Spinning is not unique at all. Make the Mario Finale green and you got "Luigi Finale", since Luigi can shoot fire as well.
EDIT: And no, I didn't type all this in one sitting. I wrote some, stopped, wrote more, stopped again, then wrote more.