Honestly, I find Salamence harder to deal with than Garchomp. Why? Versatility. All Garchomp sets that were any good used Garchomp's physical prowess to sweep teams, either with Swords Dance or a Choice item. Because of this, I was able to counter 95% of Garchomps with my Lapras (which would fall under the "bulky water" category).
Salamence on the other hand uses several sets, all countered by different things and each with massive destructive power. Should I bring Lapras out into Salamence as I so readily would against Garchomp, I get mixed results. Sometimes, Sala uses Dragon Dance. When this happens, Lapras counters Mence because a DD Outrage won't OHKO, but a STAB 4x Ice Beam will. Sometimes, Mence uses a physical attack immediately, like Outrage, Earthquake or Fire Fang. When this happens, I still win because Lapras can survive the Outrage it came into plus one more and still OHKO back with Ice Beam.
Sometimes I just get killed though. When Mence is a Meteor variety that uses Meteor as its primary or secondary attack, I get either outright killed as soon as I come in (Specs varieties), crippled when I come in (Meteor-dependent mixed varieties), or killed on the second hit before I get my first hit off (physical-dependent Meteor varieties). Any Salamence counter is like this. Any that counters a physical variety dies to a special one, or vice versa.
Any of those said sets are capable of doing incredible damage without very much trouble. Each in its own right is difficult to counter, but none alone is uber. It is the existence of several very different sets with different counters that are all near-uber that makes Salamence uber.
Salamence on the other hand uses several sets, all countered by different things and each with massive destructive power. Should I bring Lapras out into Salamence as I so readily would against Garchomp, I get mixed results. Sometimes, Sala uses Dragon Dance. When this happens, Lapras counters Mence because a DD Outrage won't OHKO, but a STAB 4x Ice Beam will. Sometimes, Mence uses a physical attack immediately, like Outrage, Earthquake or Fire Fang. When this happens, I still win because Lapras can survive the Outrage it came into plus one more and still OHKO back with Ice Beam.
Sometimes I just get killed though. When Mence is a Meteor variety that uses Meteor as its primary or secondary attack, I get either outright killed as soon as I come in (Specs varieties), crippled when I come in (Meteor-dependent mixed varieties), or killed on the second hit before I get my first hit off (physical-dependent Meteor varieties). Any Salamence counter is like this. Any that counters a physical variety dies to a special one, or vice versa.
Any of those said sets are capable of doing incredible damage without very much trouble. Each in its own right is difficult to counter, but none alone is uber. It is the existence of several very different sets with different counters that are all near-uber that makes Salamence uber.