Photosynthesizer
When in sunlight consume this item and raise speed by 1
Rain Catcher
When in rain consume this item and raise special attack by 1
Sandy Rock
When in rain consume this item and raise defence by 1
Snow Globe
When in hail consume this item and raise att by 1
Iviolite
Attack and Special Attack version of Eviolite but 10% less
Parachute
heavy-duty boosts that break when hit
Guyava Berry
when at 1/2 of less hp set stealth rock on the opponent's side of the field
Heavy Backback
ground floating pokemon and lower speed by 10%. When in gravity get 50% more defense and special defense
Castorium Z
Castform's z-move. Uses weather ball. Base 190. Changes type for different weather. Burns in sunlight, uses soak in rain, lowers special defense in hail.
Gluey Gloves
When opponent gets hit by a contact move used by this pokemon they get trapped into battle as long as this pokemon is still on the field. Consumed upon use
Reflective Shield
When hit lower the damage taken by 1/10th and reflect that damage back at the attacker. Works 3 times before breaking
Weather Machine
When in a weather, clear the weather. Works 3 times until breaking
Charger
When hitting an electric type, gain +1 spec att
Uno Reverse Card
When this item gets removed by means of knock off or otherwise, it stays held and remove the opponent's item instead
Venomous Dagger
This pokemon's contact moves loose their secondary effect in exchange for a 20% chance to badly poison.
Gunpowder
When hit by a fire move activate the effect of powder on the attacker
Flaming Torch
When held by a member of the Alolan Foongus line, boost the power of their fire type attacks by 15%
Terrain Shovel
When in a terrain , remove the terrain. Works 3 times until breaking
Green Herb
Raises Speed sharply when a Pokémon misses with a move because of accuracy. Consumed upon use.
Eject pack
When the holder's stats are lowered, it will be switched out of battle. Consumed upon use.
Room Service
Lowers speed when trick room is active. Consumed upon use.
Throat Spray
Raises Sp. Atk when a Pokémon uses a sound-based move.
Ditto Plush
Copies the opponent's item upon switch in before any effects and turns back into a Ditto Plush when switching out.
Ultra Sword
You deal 1.3x damage against Ultra Beasts (this includes Nihilego, Buzzwole, Pheromosa, Xurkitree, Celesteela, Kartana, Guzzlord, Poipole, Naganadel, Stakataka, Blacephalon, and Necrozma and all its forms)
Magma Jug
Fire type black sludge
(I really went all out on this slate lol)
Voting for Sunkern.
New Items:
Magic Powder: Doubles secondary effect rates. Doesn't stack with Serene Grace.
Competitive: Mostly just a fun item.
Burning Coal: Upon making contact with the user, the foe is burnt and the item is removed.
Venom Slime: If the holder is attacked by a special attack, the foe is poisoned and the item is removed.
Competitive: Variants of Rocky Helmet for status, but single-use.
Miner's Shovel: When the holder switches in, a single (layer) of (an) entry hazard is removed, selected randomly.
Competitive: Lots of hazards should create different ways of removing them.
Fishing Rod: Opposing Water-types can't switch out.
Competitive: Pex sucks
Spendthrift Shard: The holder has a (Level/2)% chance of not consuming PP when attacking. Effect is announced.
Competitive: Another fun thing.
Trace Orb: Negates the holder's ability and copies the foe's when coming in.
Competitive: Archeops can forfeit its ability and item to get an ability.
Dubious Mask: Lowers the foe's special attack when switching in. Single use.
Competitive: Special-Intimidate.
Giant Shell: Halves user's speed but increases attack damage by 10%.
Competitive: Slow, bulky attackers have an item to increase their speed without impacting their bulk.
Coconut Bomb: When the holder switches in, attacks for for 10% of its HP. Item is consumed.
Competitive: Juicy chip
Adventurer's Pickaxe: If held by an ice type, user ignores hazard damage, and reduces damage by super-effective attacks by 50% when switching in.
Competitive: HDB but for Ice-types because Ice-types need something here. I think full HDB would be too strong, so it's just for them.
Telescope: Against a Pokemon of higher level than the user, boosts damage dealt by 30%.
Competitive: Could be kinda fun to gimp your stats to boost power.
Heroic Medal: Against a Pokemon of lower level than the user, reduces damage taken by 10%.
Competitive: Counterpart to the above.
Tough Cape: If this Pokemon switches in and doesn't take damage, restores 10% of its HP. If this Pokemon does take damage (including hazards), item is consumed to negate damage.
Competitive: Another HDB that is single use but rewards good predictions.
Moomoo Cheese: In a pinch, this Pokemon restores 20% of its HP and the item is consumed. Is not considered a berry.
Competitive: HP restoration without needing berry abilities or effects.
Big Parasol: Negates added effect chances of attacks hitting the user.
Competitive: Item that enhances reliability by negating RNG.
Anticipation Gloves: Against a Pokemon that has a typing that is super-effective against the holder, boosts damage by 40%.
Competitive: Risky damage boosting as it is triggered off the typing of the Pokemon instead of the Pokemon's attacks.
Item Scrapper: When switching in, item is announced and consumed. The foe's item is removed.
Competitive: One-use Knock Off that removes your own item.
Scoop Up Net: This Pokemon can always switch out. On the first use, item is announced and consumed to restore 20% HP.
Competitive: Variation of Shed Shell that has some use against trapping abilities.
Cursed Shovel: When the holder is knocked out, inflicts Grudge on foe.
Competitive: Stops a snowball by shutting down an attack for the rest of the game.
I vote for Gliscor.
Tikilohium-Z: If held by a Tikilohi with Helping Souls, it can use Wrathful Soulstrike.
160BP, Ghost type, 100 Acc, Physical. If one ally has fainted, raises Attack by one stage. If two allies fainted, raises Atk and Def. If three, raises Atk, Def and SpA. If four, raises Atk, Def, SpA and SpD. If five, raises all stats.
Broken Watch: Holder's use of Trick Room lasts 8 turns instead of 5.
Plubium Z
Effect: Turns Shadow Ball into Eternal Nightmare: 155 BP, lowers all of the opponents stats
Snoxium Z
Effect: Turns Infection into Viral Freeze: 155 BP, uses the users Special Defense, Traps the target for 3 Turns
Komodonium Z
Effect: Turns Clangorous Soul into Clangorous Ascent: 150 BP, +1 Priority
Forsnakium Z
Effect: Turns Shed Strike into Shed Impact: 185 BP, uses the users Defense stat
Thundium Z
Effect: Turns Volt Switch into Returning Voltage: 155 BP, user switches after dealing damage
Anglevium Z
Effect: Turns Liquidation into Deep Sea Strike: 185 BP, summons Rain after dealing damage
Heavy-Duty-Boots
Effect: Blocks hazards
Room Stop
Effect: If any room is in effect, disables them in switch-in. Single use
As a side note the follwing items are in groups:Dark Red Emerald: Boost Fire moves by 1.5% and halves the Speed of the Pokémon by 0.5%. can not be Knocked Offed or Incinerated
Fling Damage: 70 BP
Dark Blue Emerald: Boost Water moves by 1.5% and halves the Speed of the Pokémon by 0.5%. can not be Knocked Offed or Incinerated
Fling Damage: 70 BP
Serperiorium-Z: Serperior's Z-Move, it uses Leaf Storm. Base Damage: 230, It Lowers the Speed and Special Attack of all Pokémon on the field by 2
Emboarium-Z: Emboar's Z-Move, it uses Heat Crash. Base Damage: 180, it gives this Pokémon a Attack, Defense, and Special Defense raise
Samurottium-Z: Samurott’s Z-Move, it uses Razor Shell. Base Damage: 160, Activates a Focus Energy
Gravel Berry: activates when the holder of the berry It enters the battle field and lands on stealth rocks. Ignore any damage from the rocks and remove them off the field.
Spiky Berry: activates when the holder of the berry It enters the battle field and lands on spikes. Ignore any damage from the spikes and remove them off the field.
Toxic Spiky Berry: activates when the holder of the berry It enters the battle field and lands on Toxic Spikes. Ignore any effects from the toxic spikes and remove them off the field.
Gooey Berry: activates when the holder of the berry It enters the battle field and lands on Sticky Webs. Ignore any effects from the webs and remove them off the field.
First off, please adjust your votes according to votes. I edited them after your post, so don't worry it's not your fault.I will vote for Sunkern i guess
but here are my item votes
1. Coconut Bomb
2. Uno Reverse Card
3. Room Stop
4. Magic Powder
5. All Z-Crystals
6. Broken Watch
7. Big Parasol
8. Item Scrapper
9. Spendthrift Shard
10. Trace Orb
11. Ditto Plush
12. The Berries