EM (Alt.Costume Raiden): Edenia (E-3), Fight & Defeat Raiden.
KG (Alt.Bio Raiden): Outworld (G-1), Around 5PM
MO (Dragon King Temple): Chaosrealm (D-7), 4PM Inside a hut.
MM (Alt.Bio Shujinko): Chaosrealm (G-8), Around 8AM
TE (Alt.Costume Li Mei): Orderrealm (A-5), 7PM Near where the blue path hits the grass, Fight & Defeat Li Mei.

thanks alot dude. you rule.

MO is Tanya's Alternate Costume. You have to do her mission in Outworld. Once you finish her mission, fight Smoke in Outworld C-4 and after you beat Smoke, Tanya should be standing/walking around Outworld C-2, C-3. Fight her and you get 350 Ruby Koins and unlock her Alternate Costume.
TE is Li Mei's Alternate Costume. She is walking around Order Realm A-5, B-4 by one of the gardens. Fight her, if you beat her, I think you get some Koins and you also unlock her Alternate Costume.
I'm sorry but I can't remember what EM, KG and MM have in them. Hope I helped though.
Peace Out

For the Dragon King's arena allegedly located in the house in Chaos:D7 I have heard that it's there at 5pm, 2-8pm and now 4pm. All of which turn up an empty house.
Anyone REALLY know what the accurate time and day would be? I've tried going in that damn hut so many different ways that I'm begining to think it's a big hoax that is just being passed along by people who don't know any better.

Where's Shujinko's alt costume(JO)?

i tried to fight raiden at e3 ediena i beat him but he did not give me his alt. custom can some please help on this subject.