Dead Or Alive 5: Core Fighters is the free to play version of Dead Or Alive 5: Ultimate where you have to buy each additional character for about $4 or so. While you get to use your costumes you bought for the original Dead Or Alive 5, you would still have to play for new ones.
To celebrate over 1,000,000 downloads, from now until April 21st, Dead Or Alive 5: Core Fighters will offer a complete pack can be bought for $29.99 and will include all 25 original characters and all of the costume sets from Dead Or Alive 5 and Dead Or Alive 5+. The costume sets will include 81 costumes for fighters across the entire roster.
The only thing that is not included in the bundle is the new character Marie Rose which has to be bought separately.