Changes form/boosts move power
Red Orb
Blue Orb
Shock Drive
Burn Drive
Chill Drive
Douse Drive
Adamant Orb
Lustrous Orb
Griseous Orb
Rusted Sword
Rusted Shield
Memories
Bug Memory
Dark Memory
Dragon Memory
Electric Memory
Fairy Memory
Fighting Memory
Fire Memory
Flying Memory
Ghost Memory
Grass Memory
Ground Memory
Ice Memory
Poison Memory
Psychic Memory
Rock Memory
Steel Memory
Water Memory
Stat-enhancing items
Leek
Light Ball
Lucky Punch
Metal Powder
Quick Powder
Thick Club
Z-Crystals
Aloraichium Z
Decidium Z
Eevium Z
Incinium Z
Kommonium Z
Lycanium Z
Marshadium Z
Mewnium Z
Mimikium Z
Pikanium Z
Pikashunium Z
Primarium Z
Snorlium Z
Ultranecrozium Z
While almost any Pokemon can technically hold these items, as such negating their exclusivity, the effects can only be utilized by a select few Pokemon. This is why items like the Plates are not on this list, as while only Arceus can use them to change forms, other Pokemon gain a boost to their moves.
Source
Hope I helped! If I missed anything, let me know.
