Mr. Game & Watch got in before Ridley, R.O.B. got in before Mega Man, Dark Pit got in before King K. Rool. Just because a character you didn't want got in Smash before a character you did, that doesn't mean the ones you want will never get in. I don't know why you keep making terrible statements like this, Wynn. Seriously, what do you get out of it?
I don't give a crap about Waluigi getting into Smash Bros, I'm perfecting content with him being an Assist Trophy because it's so fitting for his character. Also chosing Mr. Game & Watch and R.O.B. as examples are not good comparisons.
Mr. Game & Watch is older than Mario, that series essentially started portable gaming. The Game & Watch series is a legacy, one of the pioneers of video game history. In a series of celebrating video game history of course Mr. Game & Watch had to be a part of Smash Bros.
Comparing R.O.B. to Mega Man is different because Brawl was when third parties were extremely new so not many really knew what to expect from them, except for Sonic. Like out of all the third party character that could get into Brawl Sonic had to be on the top of that list. Also Nintendo owns R.O.B. while Capcom owned Mega Man, so comparing them on how one got in first doesn't really work well due to licensing. It's going to be a lot easier getting that characters you already own in a game than it is for a character someone else owns.
As for Dark Pit and K. Rool here that thing, Sakurai made Kid Icarus Uprising and effectively made Dark Pit. Of course Sakurai's own character was going to have a better shot getting into Smash Bros, especially with him being a clone character which requires less work to make.
And lastly let's go a little in depth why Waluigi & Piranha Plant are a good comparison.
1. Nintendo owns both of the characters, so there's no difficulty in either's inclusion when compare to third party characters.
2. They both can be considered as joke characters.
3. They both fit Sakurai's description of what kind of character he wanted to include, not a hero but not the main villain (also Waluigi wasn't the main villain in Mario DDR, he was the boss of the first level but Bowser was the final boss in that game).
4. One is part of the main Mario cast where his inclusion would effectively have made every major Mario character playable in Smash Bros, and one is literally generic enemy #3.
5. Also one had fan request and the other was never asked for.
So the fact that Waluigi fill the role of what Sakurai wanted and yet still got lost to a Piranha Plant despite having a lot of things going for him is a huge indication that Waluigi is just not going to happen as a playable. It's never going to be Waluigi Time. I'm good with that.