Board Thread:General Discussion/@comment-27110495-20160107181326/@comment-27392440-20160109145708

Don't be unfair about Yammy and Yamamoto, it took 2 monstrously strong captains to beat him off screen and get badly beaten while doing it and Yama may have been a force of destruction but Wonderweiss and Barragan combined probably could've crushed him.

In regards to Grimmjow, Urahara promised him something in return for helping so it's entirely possible that Urahara might use a method similar to how he helped Ichigo  get bankai to help him get segunda etapa and the last time a segunda etapa was used it took a godlike hollow Ichigo to take him down