My understanding is that this is a Gen 5 Pokemon and only the Gen 6's get the Blue Pentagon. Basically, if you can obtain it in XY or ORAS it will have a Blue Pentagon and if it is from any other game, it does not/legally can not.
When you say Competitively, do you mean in Sanctioned Pokemon tournaments? If you are talking about any of the "Sactioned" VG's for Pokemon.com, then, no, Virizion is not legal. But for other Tournaments I am not certain. Sometimes they have tourneys with the ability to use anyone.