I guess I'll make a post on the discussion point I brought up.
Gimmicks are not for those who value consistency. They're not for those who play safe. Gimmicks are therefore not for those who wish to play tons of games with the same team on the ladder. More often than not, you will end up facing the same opponent twice, and thus your gimmicks will be less effective. When they are predictable, they lose a lot of their material and intellectual value, as your opponent now cannot be caught off-guard and lose a Pokemon, nor do they think it is different than it is.
Despite this, I contend that the best gimmicks can work on the ladder with consistency. The Liepard I posted is as hard to stop when you know what it is as when you don't. Taunt + U-turn Hydreigon (while not strictly a gimmick) will always stop Custap hazard leads. Normal Gem Gyarados will always beat Rotom-W. HP Ice Terrakion will always beat Gliscor. If these were standard and to-be-expected sets, they would still be able to eliminate these Pokemon.
I'm not saying Scarf Breloom and Scizor aren't good, but they're not anywhere near as good when your opponent knows what they are.
In tournaments, however, all gimmicks work with few flaws. Since you only have to face one opponent, well, once, you don't need more safer sets. This is where your Flame Charge Chandelure, Specs Slowking, DD Latios, etc. can shine their brightest.
Feel free to dispute my points.