Sorry but you don't have an understanding of how game development works if you think that's how things happen.
You can't just uprez existing assets for a new game like this, nobody does that in the industry and the quality would not look good. In fact, the idea of 'uprezzing' a 3D mesh created for a 7 year old game doesn't make a lot of sense for anything other than a straight port or remake, where people will be expecting lower quality assets.
Similarly, this is not in the same engine. The rigging is not reused(the skeleton system is far more robust, particularly with facial animations this time), the animations are not reused, the voicework is not reused.
The "moveset concepts" are a starting point but have to be reexamined and many characters, like Mario in Brawl or Pit in this new game, see significant changes or additions to their movesets.
If you want to directly compare a Newcomer's production to a Veteran's production, the difference is probably about a week and a half. That's how long it would take to conceptualize a moveset for the character and get approval from other branches of the company (since a lot of these Nintendo characters need approval from the individual teams who 'own' those games) and then move into production.
From there, the process of creating a Veteran or a Newcomer is exactly the same. Characters have to be modeled, rigged, and animated. Voice actors have to be hired (because reusing voicework makes no sense- if you're going to pay them full wage for a second game you're going to record new voicework), the art team has to create the effects work, which is stuff like glows or sparkles or fire or whatever the character's attacks call for that aren't part of the model itself, and then months later once the character is 'complete', or functionally complete but still missing VFX, the balance testing begins.
The balance testing is the longest, most arduous part of creating characters for a fighting game. And the worst part is, you might get it wrong and prolong the process over and over on accident.
Now, what you're thinking of? Something easy to produce? That's clones.
With clone characters, you are taking an existing rig and animations, giving it a new model and voicework, usually changing the VFX in minor ways, and bumping it up to a full character. In Smash 4 in particular, all of the clones we have seen get added were derived from alternate costumes. Doctor Mario was a Mario outfit, Lucina was a Marth outfit, and Dark Pit was a Pit outfit.
Lucas and Wolf, while they could have been produced using the clone pipeline, did not exist as costumes for other characters and therefore would have been too much work to complete in time for the game's release. (this is an assumption on my part, backed up by the comments Sakurai made about ZSS's shorts outfit revealed recently)
It's easy to get a lot of misconceptions about game development and how progression from an old title to a new title works, but believe me, this is all 100% new stuff. They can't, and don't port 'existing assets' into the game in any form other than perhaps as the non-animated trophies built out of models from other games. Anything you see in Smash Bros 4 is made for Smash Bros 4.
I'm not trying to be condescending or anything, I just think you genuinely don't realize how much work it is to produce a Veteran character, or any character, for these games. And I wanted to explain so you understand in the future for this and other titles.
As for ideas of a Bowser Jr. game, I appreciate your interest in my thoughts, but I've never considered such a thing. Although certainly, they could probably make all kinds of cool games around the Clown Car. 
