To fix, uncheck "Store EFB Copies to Texture Only". In Underwater Cosmic Mario/Luigi Race of Sea Slide Galaxy, the shell that Cosmic Mario/Luigi holds will have messed-up textures.
Problems Cosmic Mario/Luigi Holding a Shell
#Super mario galaxy 2 dolphin controls Bluetooth
This is fixed by using Bluetooth Passthrough.
#Super mario galaxy 2 dolphin controls Pc
It's a problem bound to PC hardware and driver. Seems like it might have something to do with the computer's Bluetooth dongle not granting enough bandwidth for the Wii Remote to receive the sounds and transmit controls at the same time. To remedy this, go to Dolphin Controller Configuration Window and disable (untick) Enable Speaker Data and this will mute the Wii Remote speaker, fixing the starbit slowdown problem. Wii Remote slows down when collecting starbits. This issue actually also exists on real hardware, so it's not an emulator bug.
It is the third 3D platformer in the Mario series, after Super Mario 64 and Super Mario Sunshine. Super Mario Galaxy is a 3D platform game developed and published by Nintendo for the Wii.