I've heard that adding some champagne yeast to a high gravity beer at bottling will ensure good carbonation. I have a 9.5% stout I'm bottling soon. My question is how much yeast to add for a give gallon batch? Thanks.
What yeast did you use and how long has the beer been in secondary? If the yeast has high alcohol tolerance (10%+) I wouldn't add any additional yeast. It might take longer to carb than if you added fresh yeast but since it's a high gravity beer you should let it condition in the bottle for a few months anyway.