Trick Room is generally a sub par style, that really only matches up well against Hyper Offensive teams. On more balanced / bulkier teams, switching counters into their heavy hitters in order to waste turns is generally the best bet, as well as trying to cripple / wear down the setters as much as possible. For more offensive teams its harder to deal with TR once its up, but you can easily limit TR teams to setting up TR once with the right amount of offensive pressure, and then they tend to flop to offense outside of TR. Generally Dark types such as Houndoom, Drapion, and Sneasel are pretty effective at limiting TR to being set once or twice, and Drapion and Houndoom can manage to run taunt if you are really concerned (though its generally not worth it for Houndoom, and rarely worth it for offensive Drapion).
As for the Gallade thing, right now Gallade is RU because it isn't seeing enough usage in UU or OU to be in either tier (OU because Mega Gallade is good but has so much competition for the mega slot, UU because Mega Gallade is not allowed and regular Gallade is mediocre). So because Mega Gallade is not OU by usage, and it is not allowed in UU (banned) and regular Gallade does not have enough usage to be UU, it is in RU. Mega Manectric on the other hand is OU because it receives enough usage to be OU, and therefore its base form doesn't drop.
In the near future (think Pokemon Z), we are planning on switching the way we tier, such that megas and their bases are tiered separately. So for example, Mega Manectric could be OU while regular Manectric is RU or NU.