This is…
Hypnocket (Hypnosis + Locket), the Hypnosis Pokemon, a Psychic/Ghost type,
The spirit of a deranged Hypnotised is said to reside in this Pokèmon, they're often seen hanging from trees or lamp posts, swinging from side to side, anyone who gazes up this pokemon while it's swinging will get Hypnotised, and eventually lose their mind,
by GreenScottish