(assuming he's being used as a no Nightmare backup filler) Montana/Uppers + Hugo, Willy, Pill manip, caelus and a ton of other cards beat Kolos with ease, Kolos is a very dangerous card but no one is unbeatable. Heck, even with his bonus, cards like Ray Gatline Askai zatman and almost any atk/power manip ability card with 6+ power can beat Kolos pill for pill, It's all a case of judging the situation.
Judging Kolos is a case where the pill-for-pill analysis fails completely. Kolos isn't about grinding an advantage, its about OHKO or mega bluff to drain all your pills. If you heavy pill Gatline vs bluffed Kolos = you are down 7 pills for 5 damage. You lose. Low pilled Gatline vs OHKO Kolos = you lose. You want something that can cover the 60 atk cheaply and do good amount of damage. Askai is a card that fits the Bill, the Junta 5*s are another (Emeth or Nagatar are both good).
Pill for Pill analysis is for those cards that are designed to grind advantage, and with similar damage. Is it even relevant that 1* Ceasar beats Randy pill for pill? Odds are the Randy player will throw a few extra pills anyway.