Krampus may not have a plus sign added to the end of his 9-b rating like the Grinch, but comparing their strength feats, it's obvious Krampus is stronger. The Grinch can smash wooden crates and thick ice with his physical strength, while Krampus dented a chimney. Krampus is also much faster. The Grinch is more durable, but that's the only physical advantage he has. Apart from that, he would have to use his gadgets to win. He has to use his Slime Shooter to immobilize Krampus so he can pelt him with eggs until he breaks free. After that, Grinch must use his Copter to get to a safe distance and repeat the process until Krampus is disabled, killed, or forced to retreat.
Krampus has the physical strength and speed advantages, is more experienced, can summon an army of minions (all weaker than the Grinch but still capable of interfering with his attempts to fire upon their master), can negate durability by dropping Grinch down a portal to Hell (provided Grinch is unable to switch gadgets and activate his Copter in time, assuming Krampus or the minions do not simply remove/destroy the backpack he keeps his gadgets in), and can make flight more difficult for the Grinch by using his weather manipulation to cause strong blizzards that affect the Copter's ability.
Grinch has the superior durability and much better range, can temporarily immobilize Krampus and his minions, can fly with his Copter to get to safer distance (though it will become more difficult when Krampus starts using his weather abilities), is superior to all the minions, has the intelligence advantage, and can call on Max to distract the minions and Krampus.
As for how Krampus uses his powers, the time manipulation let him rewind time to bring his victims back to life. Presumably, it won't save him if he himself dies. He can open up portals to Hell and drop his victims down them and thus negate durability. His electricity manipulation allows him to switch off all electricity in the area by disabling the landlines, making weapons that have to be plugged in useless and leaving the area dark. His weather abilities as stated allow him to create blizzards and snowstorms. His ice manipulation seemingly allows him to freeze people into snowmen (would only cause the Grinch minor frostbite as he can break out of being frozen solid in snow with only minor showings of pain). His chains may be able to restrain the Grinch for a while, as he may require help from Max to escape, though even if he can't move, he can still defend himself with his weapons or bad breath.
