You can have a mix of 11 created players and the rest being generics by default.
The closest thing to having all generics but no legends without using created players, is to just bench all of the legends. I've done this, but it's hard to even complete a pass with all generics. With created players you'll be fine, but generic WR's will make you nuts sometimes with how terrible they can be. Generic WR's are like a team of Alvin Harper's with no Michael Irvin to take the focus and make them look good, i.e. they will have trouble getting open and will drop a lot of passes being the feature WR. But if you do it, make sure you save your roster change and double-check it, because the game likes to sneak the legends back into the starting lineup for obvious reasons.
Alternatively, you can create 11 players of your own, and then select them all to your squad. This will keep all legends off your team. But keep in mind, if you create 11 players for one team it will only leave you with 9 created player slots total, so the rest of your 7 teams will have to have legends.
I know all of this sucks, but 2K wanted to make sure that circumventing the legends wasn't simple, and to make sure that doing so came with drawbacks to make the user less likely to do it.
Just hex edit the generics before putting them on your team. Use the All-Pro Editor.