Their stay at the O'dale islands has made the gang's original power skills ineffective, including their buffs. Their attacks must have the force to plow through mountains in a single blow, and some of their buffs must be powered up beyond their intended maximum levels, while naming almost each beyond max level skill with DOOM.

Heat DOOM may turn the user into a hulking mountain of strength, but the excessive heat causes great discomfort in most users. It does comfort the cold blooded users, including dragons. It doesn't affect dolls, toys, and machines.
This affects the magnitude of power skills too

Through improvising, the already disgruntled May vents her rage making her Heat more efficient, and consequently much stronger than others her size using the same skill but her top heavy and awkward body makes it difficult to maintain speed. Having a monster in his belly itself causes the 800lbs bloated Trip to have issues with gas, using the heat he can make fire bombs, but it'll hurt himself and possibly everyone else caught in the blast. Ash's tail vents heat because of he's a rat, taking advantage of that fact he can lash foes with his burning tail....but the maneuver does make him liable to miss, and that's without considering his terrible eyesight.