And that's actually kind of a massive deal-if you can be trapped and pwnd, then you can't fulfill your primary purpose.
I don't think that this is sufficient to justify that Hippowdon should always be used over Tyranitar. First, because "if you can be trapped and pwnd, then you can't fulfill your primary purpose" also apply to Heatran. Still, people use it because it is almost the only counter for Genesect, and to solve this problem, people use Shed Shell on Heatran. Why they don't do the same with Tyranitar? Because Leftovers would be missed? People used Chople Berry and don't seemed to miss Leftovers recovery many times, but the benefit of being capable to take one Fighting-type attack was a big deal. They could do the same with Shed Shell.
There is also another point. If were for this argument, then people should use other physical walls like Slowbro and Tangrowth instead of Skarmory, as the latter can be trapped by Magnezone. Before you say that Magnezone is a shitty pokémon or that it is not a big deal nowadays and that Dugtrio is extremely popular, lets say to you something: Dugtrio by itself is a massive problem for Tyranitar, but even in BW1, and start of BW2, people still used Tyranitar over Hippowdon on most occasions even considering the existence of Dugtrio. The guilty for Dugtrio's popularity now is Genesect, wich also happens to handle Tyranitar easily. As Dugtrio can handle most of Genesect's counters, and the latter is extremely popular, almost a staple on OU teams, Dugtrio by itself also becomes popular, and Tyranitar is indirectly hampered by Genesect because of this.
So Genesect is the reason, althoug is an indirect one, to why Tyranitar is receiving few credit here. Unlike some people in favor of Tyranitar being A, I am not saying that Hippowdon is effective. In fact, it is very effective for handling Dugtrio and sun teams easily. But Tyranitar is just as effective.
Mew for S Tier.
It can do anything. Setup sweeper? SDance, RPolish, CMind, BUp or NPlot away! Need a wall? It has access to healing, hazards in Private Earth, and more! Need a scout? Thankfully enough, it has both scouting moves! Want a shuffler? Mew's your guy! Need another Choice user? Have fun! I could go on.
Although Mew can do anything, this doesn't mean that it can do anything better than everything. Even the set cited above by Tabuu, Nasty Plot, I can see as having some sort of competition from Celebi, wich boasts a better tipying and has a secondary STAB that is great and in fact, makes you not worry about having to use a Psychic-type STAB in favor of a option with better coverage (but using Psychic-type STAB is still a great choice). Although Mew is not outclassed.
Mew, on my opinion, is B-Tier. It is actually amazing. Can stallbreak, can Nasty Plot, can Baton Pass... Its uses don't even end here! I've used it on my team, that had problems with SR setters and stall teams. Done; I never had problem with them again.
