Yo,
4tlas
, humor me on some math stuff here if you please. Mostly still discussing starters, so here comes the wall of text.
Now, the obvious starting place is Smashville and Battlefield. I've toyed with making one of them a CP before, but I can't really justify it. These are demonstrably and unarguably the safest and most neutral stages in the game, largely due to all of their attributes being medium. I think we can both agree that the list should be balanced around those 2 stages to the best of our abilities.
So, when you add PS2 because you have to, a couple things happen. The average ceiling height comes down, the average blastzone width goes up a bit, and the average stage width shoots up considerably(Really, this stage is crazy, I can't really explain why it's such a good neutral, cause I feel like it shouldn't be). So, the skews PS2 have created need to be compensated to keep the averages close to SV/BF.
There are a couple different ways to go about this. The 1/3/1 method has proven ineffective as all other medium stages have shown to be indefensible as starters. So all we can do is have a proportional balance where PS2 and the other 2 starters average out close to SV/BF.
Now, Atlas, your method is pretty good. Balancing the largest stage with two moderately small ones is smart. The average for stage width comes to 140.44, which is perfect(Smashville is 140.5). The average for ceiling height is 196.45 (SV is 195, BF is 200, so this is also on the nose). The one area where this is a bit off, though, is in blastzone width. This is because, in general, the small stages have disproportionately narrow blastzones than the big stages have wide. SV is 440, BF is 448, and your average comes to 427.1. I wouldn't say that's terrible, but it's definitely not ideal either speaking strictly mathematically.
So what's the alternative? Well, I started by just balancing PS2, the widest stage in the game, with WL, the smallest. This creates a hefty skew towards low ceilings and small blastzones, so to balance that, the 5th stage would be Dreamland.
*DUN DUN DUN*
Yeah, I know, but hear me out. This can work because 1. The stage itself isn't that big, it's just the blastzones. And 2. The numbers are actually pretty good in this context. Now, I know you disagree with using extreme elements in the neutrals, so I'll leave that argument for a different post as this is already getting way too long. Like I said, just humor me on the numbers. The average blastzone width on this list comes to 441.6 and the average ceiling height comes to 199.6. Both of those are in the ideal range. The average stage width comes to 143.72, which is still really close to Smashville.
Okay, that's enough rambling, I just wanted to share the number-crunching I did. Incidentally, my math landed me right on the starters already being used in AZ, so I guess it's working for at least some people lol