Hi everyone, these are my thoughts for Ridley and his chances of appearing in the upcoming game.
I really like Ridley as a villain. He is an important character who represents the Metroid series. But I believe that he will not be a playable character for Smash Bros 4. It's mainly because of Smash Bros Direct, where Sakurai mentioned that there will be other boss appearances such as the Yellow Devil on stages where brawlers fight, as a small clip is shown with Ridley's shadow on Pikachu located on the Pyrosphere stage for Wii U. This might also be another stupid joke from Sakurai, meaning that it could most likely be the clone Ridley fought in Pyrosphere from Other M or Meta Ridley from the Metroid Prime series, implying that the actual Ridley is still not out of the list. Other major reasons are that he is so huge looking at all of the Metroid games except for the first one on the NES, that he would probably be more or less the same size as the pokemon snorlax. If he is going to be confirmed, I see him being a lot like Charizard and Bowser. My last reason is that I think that Sakurai would've already added Ridley in previous Smash Bros games, mostly Brawl. Melee was understandable that he wanted to add Ridley, but it was hard to decide on whether he was a good character or bad for the game because of size and all. So instead, the director represented him in the intro of Melee. This already proves of the character's low chances. I'm not saying that he is out for sure, it's just an opinion with some proof.
I'm going to compare this situation with Palutena's. There was a picture of the day months ago, where it had a statue of Palutena on the screen as a decoration on the stage now known as Palutena's Temple. When we all saw that picture, we thought that she was a non-playable character for sure. A couple of months later, at E3, Palutena was confirmed as a playable character. In general, I see Ridley heading more towards assist trophies than anything else, but except for that, I don't see amazing things coming from Ridley.