You have Peach's Castle, Hyrule Castle, Kongo Jungle, Battlefield, Final Destination, Yoshi's Island and Meta Cavern.
That's 8 out of 9 competitive stages.
And yet in doubles/crew battes, all I see is Dream Land.
I'm back just to answer this post just in case anyone else reads it. Also I'll add Saffron/Mushroom and all the beta stages because why not as well as if I personally like the stage at the end.
You can quote all of this, idc.
Non hacked stages: Short answer, there are flaws mostly related to weird platforms and our community evolved to slower/campier gameplay.
Once legal stages (from most to least arguably.)
Hyrule Castle: See Boom vs. Gerson you're
(not) welcome. ITT you can camp on either the right/left side and people play to win. There is also a massive discussion prior to said thing/during said thing called a Treatise vs. Hyrule by Bane. It could potentially be legal for dubz though it'd need a timer/19xx mod so people just camp for 8 minutes. There is also circle camping on the top platform. I personally like the stage to an extent, especially for Falcon dittos and dubz.
Dongo Jungle: Circle camping. I.E. certain characters can't approach the top platform. See Firo vs. Wizzrobe from Apex 2014 (?.) You also cannot ledge DI due to lack of a ledge wall which limits some characters. Stage is a little too dark for old CRTs. The stage to an extent is fine for doubles but people just dislike it anyway. I kinda like it.
Peach's Castle: No grabable ledges so certain chars have even more of an issue recovering. This makes it so Pikachu/Kirby are even better there (you really want that?) Bumper/side triangles are kinda bad. Moving bad ledges. I personally love this stage.
Saffron City: Camping on the sides (especially the bottom next to the platform on the left) due to unreasonable approaches. Certain recoveries are bad due to the wells (areas where two walls meet.) Certain Pokemon (especially Venasaur and Charmander) are highly disruptive. I like this stage.
Never once legal stages:
Yoshi's Island: Circle camping if you are playing with clouds off, also hard to justify this way due to required hacks. Also a person could either be smashed (get it) or go the right platform with a lead and
reasonably refuse to approach since most recoveries are super intercept-able from the side platform. I.E. timeouts. I am semi OK with a non cloud stage.
Mushroom Kingdom: Camping on the side.
Sector Z(ero kills): Way too large, camping. lasers do 40 damage each or something like that. I hate this stage.
Hacked Stages:
In general, it's really hard to legalize a stage that can only reasonably be selected via hacks.
Battlefield: If you DI into the ledge you can die randomly. This is my personal favorite stage along with DL and would like to see it legal once everyone has 19xx.
Kirby Beta 1/Small: Platforms can be grabbed onto as if they were ledges. Otherwise it has a Congo bottom which I love. I like this stage.
Kirby Beta 2/New: Weird platform physics. There are invisible platforms. It's a testing stage for a reason. I find it weird but fun.
Tutorial Stage: Upper blast zone is ridiculously high compared to the sides. Camera is wonky. This stage is weird but OK.
Final Destination: Chars spawn right next to one another. Platforms make the game fun. I kinda dislike the stage.