Evolutionary Items

Evolutionary items are instruments that induce evolution upon compatible Pokémon.

While evolutionary items are multi-methodical in how they trigger the evolution, they are all single-use; they will be expended upon successful evolution of your Pokémon. Additionally, they are usable at any level; this makes it much safer to wait until level 100 to evolve your Pokémon if you wish to train on a lesser experience-chart disparity than its evolution, as opposed to the more precarious level-up evolutions that are sometimes nixed depending on server instabilities at the juncture.

They can be subsumed into two categories: evolutionary stones and trade-evolving items; the latter will usually have secondary, in-battle functions, too, which makes them bifunctional Held Items.

Evolutionary stones

Thunder Stone
Function Triggers an assortment of different Electric-type evolutions when expended on compatible Pokémon.
Evolvable Pokémon Obtainability Pikachu to Raichu Eevee to Jolteon Elektrik to Elektross Purchasable in every department store for 2,100 apiece Held by wild Shinx Diggable patches Kanto's iteration of Daily Challenges Ground-lootable in the Power Plant

Fire Stone
Function Triggers an assortment of different Fire-type evolutions when expended on compatible Pokémon.
Evolvable Pokémon Obtainability Growlithe to Arcanine Vulpix to Ninetales Eevee to Flareon Pansear to Simisear Purchasable in every department store for 2,100 apiece

Leaf Stone
Function Triggers an assortment of different Grass-type evolutions when expended on compatible Pokémon.
Evolvable Pokémon Obtainability Gloom to Vileplume Weepinbell to Victreebell Exeggcute to Exeggutor Nuzleaf to Shiftry Pansage to Simisage Purchasable in every department store for 2,100 apiece Held by wild Exeggcute and Tangela Diggable patches

Moon Stone
Function Triggers an assortment of evolutions for different Pokémon.
Evolvable Pokémon Obtainability Nidorina to Nidoqueen Nidorino to Nidoking Clefairy to Clefable Jigglypuff to Wigglytuff Skitty to Delcatty Munna to Musharna Held by wild Clefairy Automatically held by the NPC-tradable Nidoran Male in one of Route 2's stophouses Ground-lootable in Mt. Moon 1F Diggable Patches Rewardable in Kanto's iteration of Daily Challenges

Sun Stone
Function Triggers an assortment of evolutions for different Pokémon when expended on them.
Evolvable Pokémon Obtainability Gloom to Vileplume Sunkern to Sunflora Cottonee to Whimsicott Petilil to Lilligant Helioptile to Heliolisk Held by wild Drowzee (Berry Forest) Diggable patches Potential reward from Kanto's iteration of Daily Challenges

Water Stone
Function Triggers an assortment of different Water-type evolutions when expended on compatible Pokémon.
Evolvable Pokémon Obtainability Poliwhirl to Poliwrath Shellder to Cloyster Staryu to Starmie Eevee to Vaporeon Lombre to Ludicolo Panpour to Simipour Purchasable in every department store for 2,100 apiece

Trade-evolving items

Dragon Scale
Function It evolves Seadra into Kingdra when traded and held. In battle, it enhances the attack-power damage output of Dragon-type moves by 10% when actively held.
Evolvable Pokémon Obtainability Seadra to Kingdra Held by wild Horsea, Seadra, Kingdra, Dratini, and Dragonair Diggable Patches

King's Rock
Function Triggers multiple evolutions when held during a trade transaction, in addition to its in-battle effect of inducing the opponent to flinch in-battle at a 10% chance (if there is not already a flinch rate for the move).
Evolvable Pokémon Obtainability Poliwhirl to Politoed Slowpoke to Slowking Held by wild Slowpoke, Slowbro, Poliwag, Poliwhirl, and Politoed One-off purchasable in Slowpoke Well B1F for 15,000 Diggable Patches

Metal Coat
Function It triggers multiple Steel-type evolutions when Pokémon by a compatible Pokémon being traded, in addition to boosting the attack-power damage output of Steel-type moves when actively held in-battle.
Evolvable Pokémon Obtainability [[{{{PreEvos}}}]] to [[{{{Evos}}}]] Held by wild Magnemite, Magneton, Scyther, Steelix, Skarmory, Beldum, and Bronzor Diggable Patches