After all the threads I made for this fullgame, I never made one of the most important of all: the stages. In this thread you'll know about the stages used for AGP and all the data you should know about them, as well updates of new stages I would add for future releases.
As stated since the beginning of this fullgame and in the Public Beta 1, all the stages used are open source or with permission of the respective authors, here's the official list of the ones used for AGP. Normal letters on author's name are open source stages and italic letters are stages used with permission.
Name: Elevator
Game: Alien vs. Predator
Author: XGargoyle
(http://i.imgur.com/1RHku.png)
Name: Airport
Game: Cyberbots
Author: XGargoyle
(http://i.imgur.com/JPkyO.png)
Name: New York City Skyline (Onslaught Stage)
Game: Marvel vs. Capcom 1
Author: POTS
(http://i.imgur.com/sydit.png)
Name: Grand Finale
Game: Shock Troopers 2
Author: Winane
(http://i.imgur.com/Dp3gS.png)
Name: Shin Gouki stage (game bug)
Game: Street Fighter III: Third Strike
Author: Cybaster
(http://i.imgur.com/TsBUY.png)
Name: Wolverine's Dead
Game: Original (Marvel based)
Author: Madre
(http://i.imgur.com/hkaHO.png)
Name: Power Generation Room
Game: SNK vs. Capcom: Chaos
Author: Adzeer
(http://i.imgur.com/aEOur.png)
Name: Military Elevator
Game: Star Gladiator
Author: Enscripture
(http://i.imgur.com/4Ul8Y.png)
Name: Blockade Space *NEW*
Game: SNK vs. Capcom: Chaos
Author: Cirio
(http://i.imgur.com/vPPPMgk.png)
Name: Clone Base 2.0 *NEW*
Game: The King of Fighters 2002 UM
Author: Cosumo
(http://i.imgur.com/asPh6Sn.png)
Of course, thanks for all the creators already mentioned for make those stages and make them open source/give me permission to use them in my fullgame. Soon this topic will be updated with new stages will appear in AGP for next releases ;)