simulateAttack[g_, max_, method_, color_, r_] :=
 Table[attackplot[g, 121, max, method, color], {i, r}]
close = Mean[
   simulateAttack[Subscript[G, BA2], 20, ClosenessCentrality , Blue,
    20]];
degree = Mean[
   simulateAttack[Subscript[G, BA2], 20, DegreeCentrality , Brown,
    20]];
between =
  Mean[simulateAttack[Subscript[G, BA2], 20, BetweennessCentrality ,
    Black, 20]];

Show[close, degree, between]