Alright, I'm gonna make this post. I may add some links in places later on, but for now, let me explain myself.
Whether or not the 3DS version has more characters not seen in the leak, I believe Ridley will be released alongside the Wii U version.
First of all, before I continue, I recommend reading
this thread's OP. It explains why my argument below even has any merit.
Why? Well there's many reasons that lead me to here, let me name a few.
If you read the thread above. You would see the ever looming theme of
East vs
West and
3DS vs
Wii U. Basically what this is saying is that each version will cater to a specific audience in terms of "Exclusive" characters. If you notice on the 3DS version, we have characters that include Dark Pit, Lucina, and Shulk. Besides their niche American fanbase, these characters are unanimously categorized as Eastern characters. Then we have characters such as Ridley that are practically only have a fanbase in the Western area. Which, obviously, includes Ridley.
If there's one thing Sakurai will want to do with Ridley, it's draw out the teasing as long as possible. This is why I believe that once Sakurai and the team were at the conclusion of Wii U characters, the plan to start teasing began. I'll admit, I never said it... but ever since E3, I've had a feeling that Sakurai will draw this out up until Wii U release date. I've always had this hunch that somehow this will happen, and once I read the thread above, everything fit together like puzzle pieces.
What does Sakurai's teasing revolve around? Pyrosphere. Where is Pyrosphere? On the Wii U version. Now if the 3DS version just launches with Ridley without any sort of closure, then why tease Ridley on Pyrosphere in the first place? Obviously the first instinct is that "Well he's the boss on that stage", and that's obviously a whole 'nother argument, but I'm arguing from the opinion that he's playable.
If Nintendo reveals Ridley as playable before we get closure on Pyrosphere, the tease was useless in the first place
This is why I'm am almost positive that he will be a launch character on the WIi U version, along with Mewtwo and maybe a few more characters.
As seen in the thread above, the only way to convince/hype people for the Wii U version is characters. And I feel like the reason they're holding so much back about the Wii U's modes and exclusive features is for a Nintendo Direct before the Wii U version's release. And the only reason people will ever care for that is for the characters.
Now how will they do this? Personally, I see them having the characters be timed exclusives for the Wii U version, which if you already own the Wii U version, can transfer over to the 3DS version with the "Wii U to 3DS" button seen on the 3DS' Menus. And after two weeks, you will need to pay $5-$10 to access those characters on the 3DS without the Wii U version. This isn't screwing 3DS owners over, you're getting content planned to only be for people with both versions at a small cost. But it makes sense due to needing to sell Wii U games.
Personally, I feel this will work the same way for Wii U owners and not just be an obstacle for 3DS only owners. I'm not sure how exactly, but someway there will be an incentive to purchase 3DS version even when you only have the Wii U one (with of course, said exclusive items being available for a payment on the Wii U version)
(Also it makes too much sense to have one of the Wii U characters trailer's include Snake with a "Keptcha Waiting Huh?")