Tell me if I've missed any.
Yamask
"Each of them carries a mask that used to be its face when it was human. Sometimes they look at it and cry."
Spoink
"It apparently dies if it stops bouncing about. It carries a pearl from Clamperl on its head"
"Using its tail like a spring, it keeps its heart beating by bouncing constantly. If it stops, it dies."
Cubone
"It wears the skull of its dead mother on its head. When it becomes lonesome, it is said to cry loudly."
"It pines for the mother it will never see again. Seeing a likeness of its mother in the full moon, it cries. The stains on the skull it wears are from its tears"