If you need to get rid of 2 stages to keep an odd number of starters, then you can throw Castle Siege into Counterpicks with Delfino Plaza. Delfino is similar to Castle Siege where the stage changes often. Along with that, Delfino has walk-off edges which makes killing easy for chaingrabbers (i.e. DDD) and it has walls for d-tilt traps.
Corneria: Personally I love this stage. It's my best counterpick but I still believe that it should be banned. The main reason is because of camping. Get a character that can move along the ground (or through the air) quickly and that has a projectile and you have your winner.
Pokemon Stadium 2: This is one of those lol stages. I've never seen anyone counterpick with it. Just my thoughts about it. Not saying it should be banned or anything
Shadow Moses: You're surrounded by two walls that go to infinity. This is a very easy stage for ICs to kill their opponents without going over their chaingrab limit as well. "If the walls are a problem, then just break them down". Sounds fair enough. Right? Never mind it doesn't. To break the walls means you have to attack them making your own attacks weaker. Also it takes time to break them down. But heck let's say you're Isai and can break them with one hit, then you have another problem.....walk-off edges. I think you got the point or need I say more?
Mario Circuit: Camping. Camping. Camping. Also did I mention this stage is good for camping? Wait at the edge of the stage and your opponents will have a very difficult time approaching you. The platform on top of you (at the left and right sides of the stage) prevent your opponent from approaching from above. A character like Falco can abuse this stage too easily. Projectiles + reflector. If you attack him and you get shieldgrabbed, Falco can do a reverse chaingrab and kill you without breaking a sweat. Also a broken stage for ICs, Pit,
De
Kar, Snake, and Olimar.
That's all from me for tonight. I need to sleep. More info tomorrow if necessary.