Does the Earth Ribbon stop a Pokémon from being traded on the GTS?

[Raphetty]

This is the ribbon you get from winning the 100 battle challenge in Colosseum I think. I was not able to trade my Rhyperior or Moltres which had this ribbon. The message I get is: It's a special Pokémon. You can't trade it!

[Sceptile987]

I think it's more of a case where it thinks the pokemon originated from Colosseum rather than the handheld games, and has mistaken it for an event pokemon

[Raphetty]

I think it's more of a case where it thinks the pokemon originated from Colosseum rather than the handheld games, and has mistaken it for an event pokemon

No, I have checked various online sources and it is the ribbon that stops the GTS trade. I have a Rhyperior which originated from the Hoenn region (before it evolved), got the ribbon from training it at Mt. Battle in Colosseum and now it can't be traded on the GTS.