They're much bigger here than you seem to think! I've struggled even getting preorders for some on the very first day they go up.
No, he sold out long ago. I tried to get a preorder of him for Justin like a fortnight before he even came out but had no luck both on and offline.
I can only really speak for what I've seen in-stores in Glasgow and Ayrshire, but:
Smash line:
I've seen Mario, Luigi, Peach, Link, Pikachu, Samus, Yoshi, Donkey Kong, and Diddy Kong in several game shops even weeks apart. They seem pretty easy to get hold of.
I've seen Toon Link, Ike, Zelda, Lucario, Bowser, Sheik, and Captain Fox in stores, but I can't recall how recently that was. Zelda and Bowser are the ones I can recall seeing most frequently. The shops I saw Lucario, Ike, Fox, and Toon Link in had quite a lot of them but I don't know if they still would now. Sheik I think I saw in only one or two shops a week or two after the release date, but they didn't have many.
Super Mario line:
Super Mario line seems readily available. I went into one GAME shop a couple weeks ago and they had all six.
EDIT: oops, forgot Sonic. I saw quite a lot of him last time I went into GAME too.