I won't deny there are people who want Waluigi because of the memes, and I do agree with you that there's more to the character than just that. I have seen some creative movesets made that shows what Waluigi is capable of. In regards to Waluigi's moveset. I believe that three major things need to be taken note of in order to make a great moveset.
First is the origin of Waluigi, he was made to be Luigi's doppelganger and Wario's partner. So obviously there has to be moves from Waluigi that reflects this aspect of him, perhaps some aerials or Smash attacks would resemble moves from Wario and Luigi. The second aspect is his spin-off role. Waluigi is mainly used in the spin-off games. Hell, he was originally made for Mario Tennis, a spin-off game. Since we have yet to have a character that incorporates the Mario spin-offs in their movesets, Waluigi could very well do that since it fits his origin role, which is him being used in spin-offs. For example, he could use Tennis in one of his specials as a projectile. The third and final aspect is his cheating personality. Waluigi's animations and moveset should resemble a playstyle where he plays dirty and is generally not honest. Perhaps you could give him his stomping move that he uses in his assist trophy to ground opponents or spike them in the air, that's just one example.
If the memes trouble you then that's fine, I get where you're coming from. But let's be honest with ourselves, do we REALLY think Sakurai is gonna put WAH as his side special? Obviously not. And if I were you I wouldn't trouble myself over these things. Instead I'd look at the positives and the potential that the character has.