According to PTCG official, BW3 Shiftry was banned.
Pokemon.com ( Shiftry-banned )
[ Point Quotation ]
Shiftry's previous Evolutions, Seedot (XY?Flashfire, 5/106) and Nuzleaf (XY?Flashfire, 6/106), are Grass-type Pokemon, so it's possible to evolve to Shiftry in one turn using the Forest of Giant Plants (XY?Ancient Origins, 74/98) Stadium card. With the help of Devolution Spray (Black & White?Dragons Exalted, 113/124), Super Scoop Up (XY?Furious Fists, 100/111), and Recycle (Black & White?Emerging Powers, 96/98), players can use the Giant Fan Ability repeatedly to get rid of all of the opponent's Pokemon?and win the game in one turn.
In japan, There is not announced yet. These were the pair(shiftry-Giant plant forest) that many players were seeing as a problem, they waited for official correspondence. As a result, it became the banned card.
Oh well, I don't understand the differences between the ban and prohibit 😛