Oh no, not another Ridley debate...
I can understand both sides, however. The fact that he was never completely revealed as a boss character and Melee's intro shows possibility. Bowser's been scaled to many different sizes, why not scale down Ridley just for this game? Another Metroid rep would be great. And Sakurai loves to troll us fans. He could be making us all think that he's a boss, then give a surprise announcement that he was a playable character the whole time. xD
On the other hand, Ridley's consistently huge. Scaling him down would make him look really awkward compared to the rest of the fighters. He's supposed to be big and menacing. In Metroid Prime 3, he was big enough for Samus to stand in his mouth. And him being a boss in Brawl with an already defined Smash size even further questions his playability. Maybe they could use Prime 1's Meta Ridley (his "smallest" model?), but that's it as far as I'm concerned. And I don't see them using it since they're using Samus' Other M model, and Ridley was pretty big in that game. Plus the Other M Ridley model is already the confirmed one they're using.
I really do want him playable and would love to see it happen. I'm all for it, but at the end of the day, I just doubt they'll do it. I still think he's a boss in the Geothermal Power Plant stage. If I'm wrong and he is playable, I'll be excited. If he isn't, I'll have expected it.