Okay now we all know that Speed Boost Blaziken got banned from Smogon, so here's another new candidate that is likely to get banned as well and it's Prankster Riolu. The reason why it's so broken is because of this scenario:
Setup Stealth Rocks, Leech Seed, Toxic Spikes, or two of each. Then switch into Riolu in order to use Roar, because of it's Dream World Ability Prankster Riolu gets priority to use Roar first before the Defending Pokemon gets to use a move regardless how fast it is. Knowing that Riolu is going to take a hit it's holding a Focus Sash so that it can use Copycat to copy Roar to pretty much sweep the opponent's team.
Because of Stealth Rocks and Toxic Spikes their Pokemon takes damage until they are KO'ed. Unless you can counter Riolu with a Priority move like Sucker Punch with it having 1 HP left you're screwed. No matter what attack you deal Riolu's Prankster will ensure that it's attacks go off for the rest of the battle until you've won, not even Rapid Spin works cause it doesn't have priority.
Setup Stealth Rocks, Leech Seed, Toxic Spikes, or two of each. Then switch into Riolu in order to use Roar, because of it's Dream World Ability Prankster Riolu gets priority to use Roar first before the Defending Pokemon gets to use a move regardless how fast it is. Knowing that Riolu is going to take a hit it's holding a Focus Sash so that it can use Copycat to copy Roar to pretty much sweep the opponent's team.
Because of Stealth Rocks and Toxic Spikes their Pokemon takes damage until they are KO'ed. Unless you can counter Riolu with a Priority move like Sucker Punch with it having 1 HP left you're screwed. No matter what attack you deal Riolu's Prankster will ensure that it's attacks go off for the rest of the battle until you've won, not even Rapid Spin works cause it doesn't have priority.