I will be answering this in a series of answers.
In Pokemon X/Y series, a blue pentagon can be seen next to your Pokémon('s) while viewing the status screen in trades, the box, and so on. It was initially unclear what it was intended for, but it's hack checkable.
Game Freak included the pentagon to be a ''hack checker'' of sorts. Pokemon who have the ''pentagon'' are confirmed to be legitimate. If the Pokemon doesn’t have the blue icon, that means there was an error and it has been hacked.
Pokémon pentagon's shouldn't be a ''put off '' sign for using them as others are legit but also used (e.g from other game genres) and if stats/natures/movesets including ID and OT off of black2white2 are seemed legit then there's no real way of finding a viable source of info on the subject.
2011 January 3rd-January 9th @ Gamestop Shiny Raikou- January 3rd-January 9th
•Held Item: Micle Berry
This Pokemon has been hacked and aslong as you include it's movesets, nature and ability within a cherish ball (event ball) then it's seem as legit, which is my point...
A good way to test is to put it through the GTS.
Pokémon x/y poke bank is a Pokemon legitemency checker. Simply go to e-shop on Nintendo store and purchase the poke bank (depending on what country you live in couherses with the currency they require for payment)
GB - £4.49
Eur - €4.99 in Europe.
AU - $6.50
NZ - $8.50
Source = Experience (had same issue myself :)
Hope I helped!