Required positions:
QB, RB, WR, TE, T, T, G, G, C
DE, DE, DT, LB, LB, CB, CB, S
K, P, KR, PR
.
That leaves 2 skill positions on offense for whatever type of offense you want - FB and/or RB and/or WRs.
.
It also leaves 3 positions on defense for your base D to include NT and/or DT and/or LB and/or S.