Havok and Mastermind are Beta mutants, or the following reasons:
Havok: Their powers are not as uncontrollable as those of Scott, but even so, he needs his concentric circles to know whichever energy has thus stored and to avoid an overload. If outside Alpha, would not have to worry about those things.
Mastermind: Mastermind could fall victim of his own illusions, if he did not have well-taken care of. His daughters yes who I see alpha them.