Montana can be somewhat of a pain, but they're not as bad as they seem. High-damage clans all have a lot of cards that strip them of their advantage.
Freaks: Pill manip cards that negate the 2 pill advantage upon winning. High power.
FPC: SoB/CoB, power manipulators that have 7 power and reduce down to a min of 4. (At least a few of these cards are essential in an FPC deck, or you will get trampled by *any* attack manip clan.)
Junta: A bit tricky to play against
Montana, but then again, they are a bit tricky to play against everything. Many good Junta cards are only at a small disadvantage against them, if any, due to some power or attack manip.
Ray,
Naginata,
Pilzken,
Tolliver,
Gatline,
Trish,
Isatis,
Thormund, etc etc etc. (SoA presents a much bigger problem for Junta, but fortunately they have some great Stop cards.)