So they changed they rule sets around in a way that really bothers me.
In order to use legendary ubers (Mewtwo, mew,lugia,ho-oh, celebi, groudon, kyogre, rayquaza ETC). you must choose no restrictions,
However doing this removes the lvl 50 all clause as well, so All my pokemon that I Trained that are not maxed out to lvl 100 (Should I ever choose to change EVs) will be at only level 50. when some of them may be lvl 100 on the other side.
also the items clause is removed as well as the species clause

As of yet you can't alter EVs in B/W anyways, unless those berries become available in DW. It may be more difficult but with the feathers you can reEV at level 100 since you can use them after 100evs to max a stat.

Aside from 6 Arceus teams, team preview kills the surprise factor of having two or more pokes, so I don't see the species clause being super necessary.