I think everything except for BCV, AKV, and Bay Lake. So that leaves Old Key West, Saratoga Springs, Villas at Wilderness Lodge, Boardwalk Villas. There are also certain times of year when you cannot pool hop at all.
You can pool hop to any pool on Disney property except:
Swan and Dolphin pools - not operated by Disney
Shades of Green - not operated by Disney
YC/BC/BCV - none of these pools are permitted for pool hopping
AKL/AKV - neither of these pools are permitted for pool hopping
BLT - I don't think this one has been officially noted as off limits (as well as CR pools)
Pool hopping is usually blacked out during holiday periods for the days before and after. Check your latest Disney Files for the exact dates. Also, should the lifeguards determine that the pool is crowded, they can ask you to leave.