Obviously I'm pro banning Garchomp. In a Metagame we have in BW, especially in BW2, it's incredibly hard to cover or check all the threats that run around. You allways have to fear being swept by a powerfull sweeper, so having another of those sweepers makes teambuilding and playing incredibly hard and imho it's not enjoyable to play in such a metagame.
Sand Veil makes it even harder to get past Garchomp and even the most skilled player may fails to kill it due to some unfortunate misses, so I think it's worth banning Sand Veil as well.
There is no excuse for who you are