Nope, but it won't be the first time they added a 3rd party char to SSB (plus castlevania has been on more nintendo consoles the sonic and snake has)
I know it wouldn't be the first time they add 3rd party characters to SSB...
Sakurai has been adding characters for three reasons: for their popularity, to be advertized, or to show that Nintendo is in good terms with another company. I'll explain.
Most of the characters have been added for their popularity (Mario, Link, Samus and all the other Nintendo all-stars). Some characters were added to be advertized because SSB happens to be a really powerful advertisement platform. Take Roy and Marth as an example. Roy was added to the roster before even making an appearance in Fire Emblem. Roy's and Marth's popularity was so big they chose to release Fire Emblem outside Japan.
The third reason is the one concerning 3rd party characters. Sonic has been added to the roster because Sega was in good terms with Nintendo. Sega has released Sonic Colors, Sonic and the Black Knight and Sonic and the secret Rings, namely, on the Wii. This showed that Sega and Nintendo we're doing well together. Sonic's inclusion in the roster kind of sealed this "friendship". For Konami, the inclusion of Snake was a proof that they weren't in bad terms with Nintendo. They soon released a remake of Metal Gear Solid 2 or 3 (I don't remember) on the 3DS.
A company that makes a lot of games for a Nintendo console shows support. A company that stopped to do so shows the opposite. Your reasoning was wrong.
I was wrong about Castlevania support though, they released many games on Nintendo consoles, so seeing a CastleVania character would indeed be really likely, but, again,
"And toon link, fox mcloud, falco longbird, wolf, Ike, olimar, pokemon trainer, Samus, DK, diddy kong, mr game and watch, pit etc never appeared on thewii before ssbb came out. Yet they appeared on the game"
is totally wrong and lacks logic.