While something definitely should be done if the Pokemon can be discovered to be hacked, it is difficult to verify that they are hacked when actually looking at the Pokemon's data. I know how to create hacked Pokemon and Action Replay codes for such, but I would never use them in the GTS. If you ever come across a Meloetta, Keldeo, or Genesect in GTS, then it's 100% sure they are hacked because they have not yet been officially revealed. When viewing other Pokemon's data to verify that it is hacked, however, the only way to verify it is if the creator made a mistake in creating it, such as forgetting to specify a language origin, hometown, or meeting place. Also, if it shows for the met date as "0/0/2000" that is a sure sign of being hacked. Overall, I do think something should be done, but doing so is, in most cases, rather difficult.