You can only prove so much, but when the opposition refuses to listen, there's no point in carrying on. That and the discussions of Classic/Toon Link are stupid, they're both a second Link and both shouldn't be in the game. Not to mention there are alot of others that have explained it better than I have, so I'll in turn let them say it. Also, when you come home from the dentist after having a couple of cavities filled in, you don't really feel like continuing useless debacles...I just got home from the dentist after having a couple of cavities filled in and I don't feel like continuing useless debacles.
If you find discussions of Classic / Toon Link stupid, why do you choose to create them by saying that you expect Classic Link over Toon Link?
I have no issue with your preference, everybody has a right to say "Hey I'd love to see this character because I like him / her / it". But suggesting that Classic Link, a character who looks more like the regular Link we see in Smash in body type is more likely than the more popular and cartoony-proportioned Toon Link who would be a returning veteren.
The point is you can't prove it, it's basically the same character with different designs, and which ever character people think is better is determined on someone's opinion. And if you think you can try and prove people's OPINIONS wrong, you look like a Grade A Douche-nozzle, especially since both characters have reasons to be in the game and not be in the game at the same time.
I suppose I can try to prove it then.
Link to Classic Link
They share the exact same Sword and Shield, with both designs being EXTREMELY similar (If not the same for the Sword).
Classic Link's tunic is very basic and simple in comparison to Links. They both have leggings and fairly similar boots though. But their body type and general design are just far too similar, it would really just be another case of Young Link.
Link to Toon Link
Toon Link is just very different from Link (Despite this being a beta colored image, it was the only one with a pose with both his Sword and Shield visible). The head, legs, eyes, body type, and shield are remarkably different. We can't also forget that is color scheme and overall style is unique too (With his shirt color normally being a lime green). His overall size and design are very different to the Link we have in SSBWU/3DS. This is why he would make much more sense as a playable character, being a clone or not.
There are far too many people who complain about two Links as it is, but replacing the visibly different one with a more similar looking Link is just begging for trouble (Especially when the previous one is then changed to become Downloadable Content in your roster Hotfeet).
Especially when you suggest that he could use more of his unique items in his moveset when Toon Link not only has more at his disposal, but he also has
access to several of Classic Link's as well. Toon Link just is the more logical character choice due to both his veteren status and unique body type in comparison to the already existing Link.
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Another thing I want to touch on is Sylveon. Now I'm not saying that Sylveon isn't likely, but I'm saying that it is a
very odd character choice. You say that the Eevee Family is very important to the Pokemon franchise. But if that was the case, why haven't they received anything else other than getting Eevee as a trophy in Melee and Glaceon and Leafeon sharing a trophy in Brawl?
I think we would probably see Sylveon to be a Pokeball Pokemon before being a playable character and I think this would be the logical thing to do. As it seems to be branded as the first Fairy type Pokemon, it makes sense for it to represent Fairy type Pokemon using Moonblast. As Jigglypuff, an already existing playable character, be allowed to utilize the Fairy type moves. It just seems like the better thing to do to me.
You need more than that to prove that Toon Link is better. It's like saying Dr. Mario is better to represent because he's stronger and has some of normal Mario's moves, it just don't work like that. 
