GBC (or Good Bad Corners) is a 2x2 speedsolving method using COOpposite and PBL.
However the method is the same as Guimond Method with it just reduced the cases for first to step by orient entire face then OLL instead of orient 3 corners on D layer then solve rest of the orientation using 1 algorithm.
You can see if a corner is good or bad by looking at the bottom and top stickers. The key sticker is yellow/white. Example : if 2 bottom stickers have white or yellow, they are good. If they have any other colors, they are bad. To fix the bad corners, we will use Sexy Move or Reverse Sexy. For the top ones, just use normal OLL.
The Unmixing part is probably the easiest part of the method.
- Sometimes, you will get an L-shape
- If you have two yellow corners that are not adjacent on the top and a yellow corner bar on the bottom
- If you have the same case as case 2 but with the bar on top
- If you have two non-adjacent yellow corners on both top and bottom
- If you have yellow corner bars on both top and bottom, put the top one at the left and the bottom one at the right, then do R2.
- If you have the first case but yellow is inversed with white,
It's just normal PBL.