Its kind of inconvenient for me because usually I just get my team planned out so I dont know that yet.
IVs aren't required, since you can't change them, and for the simulator they're always 31.
EVs are required because movesets will differ depending on the Pokemon's role. However DT is right - if you say what the role of the Pokemon is going to be then that's fine. So say whether it's a physical sweeper, special sweeper, wall, tank, etc.