Popping in real quick to give my ratings...
Day eighteen--Springy arms and musical charms.
ARMS Character
Chance: 90%
New IP with a very unique mechanic and a great character design? That is Sakurai's bread and butter right there. I remember him making a remark once about All Star, and how big of a new IP gap there was between Pokemon (I think) and Pikmin. He jumped on Shulk, despite JRPG characters being unusual to smash. There's no way he didn't hear about (or was told about) ARMS, and no way he didn't immediately see how viable the characters are for Smash. Then there's the Nintendo factor--they have poured a TON of effort into promoting ARMS, and there is literally no better way to promote any game or series than putting it in Smash, hands down (I'm sure even Ice Climber's sales went up on the eShop, if only a little bit.)
So, I'm afraid, salty people who--for whatever inconceivable reason--have an issue with ARMS in Smash, this is one series who is most likely to be included. The "timeline" argument doesn't hold water when you're talking about internal development and marketing teams at Nintendo, who have their hands so deep into any possible plans for Smash that there is no way that the ARMS characters they developed/were developing/marketing would not be brought before Sakurai.
The only reason it doesn't get 100% is because there is some SLIGHT possibility that Nintendo was unsure if the series would live. That's it. But I've never been this sure of a character's inclusion in Smash before.
Oh, and for the record, I'm predicting Spring Man as a starter, with Ribbon Girl as an unlockable semi-clone. Mark my words.
Want: 100%
I Mean, duh. I still can't see how anyone, even non-ARMS fans, could possibly reject the idea of them being in. "Oh, a new IP oozing with personality and moveset potential? Ick, no! I want a a single obscure character from a longstanding repped franchise!" Really now, who would say that? New IP is always good for Smash, bar none. I'd even be open to something as uninteresting (to ME, let me be clear) as Style Savvy getting a rep over, say, more Fire Emblem or Pokemon.
Which segues nicely into our next entry...
Rhythm Heaven Character
Chance: 65%
It pains me to give that rating, but it must be done. Rhythm Heaven has been around since the early oughts, but still, Sakurai denies its potential. Past experience tells me there is much doubt to be had.
But there is hope--RH could supply the ideal WTF character. You KNOW it's a given. Every Smash has had at least one. And now that Wii Fit Trainer is old news, we need a new one. The main competition for RH in this category would be a Labo character, which is a very real possibility--but RH also has the advantage of being viable as a retro rep, too. Plus, of course I must bring up the Sneaky Spirits in Smash Run--one of very few, if not the only, series without a rep to get an enemy. I feel that's still significant. This is why it gets 65%.
Want: 100%
Old supporter of Marshal, right here. Really though, anyone works for me. I love this series, and every new release is a big deal to me, along the lines of Kirby and Sonic.
Predictions
Daisy: 11%
Paper Mario: 5%
Nominations
Marx x5