This isn't about Konquest, because it has already been said and done. I'm talking about practise mode, with you testing out existing characters. I think practise mode SHOULD be in MK:D, but the approach of it should be more evolved. It should be called Sparring Mode, because that's what it is basically. You should be able to choose between Shadow Sparring (Sparring by yourself) and normal sparring.
With Shadow Sparring, it should either involve you hitting the wooden block thingy (martial artists should know what I'm talking about), targets forperforming projectile attacks or just performing aKata. For Dual Sparring, you should be able to choose the difficulty rating for the CPU, to turn on and off the CPU function, a command list and commands for what the computer to do if you don't want the CPU function. Also, there should be a function when you press an unused button (Select on the PS2, for example), some "Fatality/Hari Kari Time" is alocated for you to practise Fatalities and Hari Karis (Hari Karis would be performed via the second controller).
Also, when you perform a certain combo, special move or Fatalities, it should tell you what you just performed and the button combination to perform that move. It might not seem like an important mode, but if some one wants to test out Sindel in her 3D glory before hitting arcade/online mode, it must be as flexible as the rest of the game is sounding out to be.