Shell Bell: What doesn't activate it? I know Doom Desire, Future Sight, and any other end-of-turn damage does not, but other than that...
Just tested in the Battle Tower. Shell bell is not affected by Pain Split.
My Gengar Hit Dusknoir with Psychic, did around 80%
Then Dusknoir Pain Spilts an opposing Squirtle, healing itself, but Shell Bell didn't kick in.