They were there before, right?
Yes , the stage changes are the following,
All stages
-Collisions have been added to all walled stages (walls that go past the blastzones) to prevent going inside the stage during the new Stamina Mode
Castle Siege
-No longer skips second portion
Distant Planet
-Changed the base model from the SSE to a custom tree trunk, leaving the collisions similar besides the slopes on the walls
-Retextured the platforms to be wooden
Dreamland
-Completely new model, but has the same properties as 3.02
Frigate Orpheon
-Added right ledge to first transformation
-Raised center platform of second transformation
Hanenbow
-Completely redesigned for Turbo Mode
Hyrule Castle
-Completely new model with different collisions and a raised ceiling
Infinite Glacier
-Completely redesigned for semi-competitive play
Jungle Japes
-Indefinitely removed from Project M
Lylat Cruise
-Added left and right wall collisions to the ceiling of the stage just underneath the ledge to make it slightly more lenient to jump from the ledge
Metal Cavern
-Completely new model, but has the same properties as 3.02
Norfair
-Redesigned for competitive play in mind
-2 platform stage with a base the size of Smashville
-The 2 platforms have a desynchronized pattern they follow
-Raised the lava up to match the blast zones
-Blast zones have been slightly shrunk from 3.02 Norfair
Pokémon Stadium 1
-Modified the camera to not zoom out during the transitions
Rumble Falls
-Stage now starts slightly down the waterfall and rises up to the original position in the first minute
-Stage is now 90% of its 3.02 size
Skyloft
-Music titles now appear at beginning of match
-Now has a second music slot (Tal Tal Heights)
Skyworld
-Added left and right wall collisions to the ceiling of the stage just underneath the ledge to make it slightly more lenient for ledgehopping
-Shrunk the base vertically so it’s skinnier
-Fixed the model on the left side of the base to match the right side
Training Room
-Can now spawn items
Yoshi's Island: Brawl
-Ghost platforms have been put on a timer. Each comes up every 25 seconds
-White Shy Guys appear, signalling the arrival of ghost platforms.