The Big Ol' List of Gen 7 Field Changes (Patreon)

this was yesterday's project. bewearof  low-flying text walls, and note this is all very much still subject to change

* -- Electric Field

• Galvanize's boost becomes x1.5 (from x1.2)
• Activates Surge Surfer
• Disables Comatose
• Hydro Vortex gains Electric-type damage
• Created by Electric Surge
• Created by Stoked Sparksurfer for 3 turns
• Destroyed by Tectonic Rage
• Elemental Seed boosts Defense and applies Charge to the user

* -- Grassy Terrain 

• Floral Healing heals 2/3s target's HP (from 1/2)
• Nature's Madness deals 75% HP damage (from 50%)
• Created by Grassy Surge 
• Created by Bloom Doom for 3 turns when not in Forest or Flower Garden Field
• Transformed into Corrosive Field by Acid Downpour
• Transformed into a Burning Field by Inferno Overdrive
• Elemental Seed boosts Defense and applies Ingrain to the user

* -- Misty Terrain 

• Misty Terrain now blocks confusion
• Activates Water Compaction on send out
• Soul Heart additionally boosts Sp. Def on use
• Moongeist Beam damage increased x1.5
• Created by Misty Surge
• Destroyed by Supersonic Skystrike
• Transformed into Corrosive Mist by Acid Downpour
• Elemental Seed boosts Sp.Def and applies Healing Wish to the user

* -- Dark Crystal Cavern

• Solar Blade always fails
• Enables Aurora Veil
• Moongeist Beam and Shadow Bone damage increased x1.5
• Prismatic Laser and Black Hole Eclipse damage increased x2
• Prism Armor and Shadow Shield Pokemon take x0.5 decreased damage
• Transformed into a Cave by Tectonic Rage
• Magical Seed boosts Sp.Def and applies Magic Coat to the user

* -- Chess Board 

• Continetal Crush becomes a Chess Attack
• Pokemon with Queenly Majesty deal x1.5 damage
• Destroyed by Stomping Tantrum and Tectonic Rage
• Synthetic Seed boosts Sp.Atk and applies Magic Coat to the user

* -- Big Top Arena 

• High Horse Power, Ice Hammer, Dragon Hammer and Continental Crush become High Striker attacks
• Spotlight rasies the Attack and Sp. Atk of both its user and target
• Revelation Dance, Fire Lash, Brutal Swing, Stomping Tantrum and First Impression damage increased x1.5
• Dancer boosts Speed and Sp. Atk every time a dance move is used on its own turn. 
• Synthetic Seed boosts Attack and applies Helping Hand to the user

* -- Burning Field 

• Restores Fire type to Burned Out Pokemon each turn
• Fluffy Pokemon take 2x Field Damage
• Water Bubble Pokemon are immune to Field Damage
• Destroyed by Continental Crush, Hydro Vortex, Oceanic Operetta and Sparkling Aria
• Elemental Seed boosts Sp.Atk, Atk, and Speed and applies Fire Spin to the user

* -- Swamp Field 

• Activates Water Compaction each turn
• Strength Sap heals 30% more HP
• Hydro Vortex gains Poison damage
• Telluric Seed boosts Defense and Sp. Def and applies Ingrain to the user

* -- Rainbow Field 

• Sparkling Aria, Fleur Cannon, Prismatic Laser and Twinkle Tackle damage increased x1.5
• Never-ending Nightmare damage decreased x0.5
• Enables Aurora Veil
• Prism Armor Pokemon take x0.5 decreased damage
• Soul Heart additionally boosts Sp. Def on use
• Magical Seed boosts Sp.Atk and applies Healing Wish to the user

* -- Corrosive Field 

• Floral Healing additionally poisons its target
• Corrosion Pokemon deal x1.5 damage
• Activates Merciless
• Telluric Seed boosts Attack and applies Baneful Bunker to the user

* -- Corrosive Mist Field 

• Sparkling Aria gainst poison damage and damage increases x1.5
• Floral Healing additionally poisons its target
• Corrosion Pokemon deal x1.5 damage
• Activates Water Compaction on send out
• Activates Merciless
• Destroyed by Supersonic Skystrike
• Combusted by Inferno Overdrive
• Elemental Seed boosts Attack and Sp.Atk and badly poisons the user

* -- Desert Field 

• Shore up restores 66% HP (from 50%)
• Burn Up damage increased x1.5
• Telluric Seed boosts Defense, Sp.Def and Speed and applies Sand Tomb to the user

* -- Icy Field 

• Enables Aurora Veil
• Liquid Voice's makes attacks Ice type instead of Water.
• Lunge boosts Speed on use.
• Activates Slush Rush
• Transformed into Water's Surface by Inferno Overdrive
• Elemental Seed boosts Speed two stages

* -- Rocky Field 

• Long Reach Pokemon suffer a x0.9 accuracy loss
• Accelerock damage increased x1.5
• Telluric Seed boosts Defense and Sp.Def and damages the user with Stealth Rocks

* -- Forest Field 

• Long Reach Pokemon suffer a x0.9 accuracy loss
• Strength Sap heals 30% more HP
• Nature's Madness deals 75% HP damage (from 50%)
• Transformed into a Burning Field by Inferno Overdrive
• Telluric Seed boosts Attack and applies Spiky Shield to the user

* -- Super-heated Field 

• Hydro Vortex, Sparkling Aria and Oceanic Operetta generate steam on use
• Destroyed by Subzero Slammer
• Telluric Seed boosts Defense and applies Shell Trap to the user

* -- Factory Field 

• Gear Up's effect is doubled, and additionally boosts its user
• Galvanize's boost becomes x1.5 (from x1.2)
• Steelworker's damage boost becomes x2 (from x1.5)
• Transformed into Short-circuit Field by Tectonic Rage and Gigavolt Havoc
• Synthetic Seed boosts Sp. Atk and applies Laser Focus to the user

* -- Short-Circuit Field 

• Galvanize's boost becomes x2 (from x1.2)
• Steelworker additionally makes all attacks gain Electric typing
• Activates Surge Surfer
• Shadow Bone damage increased x1.3
• Hydro Vortex gains Electric-type damage
• Transformed into Factory Field by Gigavolt Havoc
• Synthetic Seed boosts Sp. Def and applies Magnet Rise to the user

* -- Wasteland 

• Pokemon with Corrosion may trigger the field's random statuses on any Pokemon regardless of typing.
• Activates Mercliess
• Acid Downpour additionally applies a random status to non-Poison/Steel types
• Telluric Seed boosts Atk and Sp Atk and applies a random status to the user

* -- Ashen Beach

• Shore up restores 75% HP (from 50%)
• Water Compaction additionally boosts Sp. Def on use
• Telluric Seed boosts Critical Hit rate and applies Laser Focus to the user

* -- Water Surface 

• Shore Up activates Water Compaction
• Schooling is active at all times
• Activates Surge Surfer
• Activates Water Compaction each turn
• Hydro Vortex damage increased x1.5
• Transformed into Icy Field by Subzero Slammer
• Transformed into Murkwater Surface by Acid Downpour
• Elemental Seed boosts Sp. Def and applies Aqua Ring to the user

* -- Underwater 

• Schooling is active at all times
• Activates Surge Surfer
• Activates Water Compaction each turn
• Anchor Shot damage increased x2
• Transformed into Murkwater Surface by Acid Downpour
• Elemental Seed boosts Speed and applies Soak to the user

* -- Cave

• Prism Armor Pokemon take 33% damage from the collapse
• Tectonic Rage and Continental Crush contribute to the cave-collapse count
• Telluric Seed boosts Defense and damages the user with Stealth Rocks

* -- Glitch Field

• Created for 5 turns by using Conversion and Conversion2 in succession while not holding an Everstone
• RKS System's type becomes ??? at all times
• Synthetic Seed boosts Def and Sp. Def and makes user ??? type

* -- Crystal Cavern 

• Prismatic Laser and Multi Attack gain crystal's type damage and damage increases x1.5
• Moongeist Beam damage increases x1.3
• Prism Armor Pokemon take x0.5 decreased damage
• Enables Aurora Veil
• Transformed into a Cave by Tectonic Rage
• Magical Seed boosts Sp Atk and applies Magic Coat to the user

* -- Murkwater Surface 

• Shore Up activates Water Compaction
• Schooling is active at all times
• Activates Surge Surfer
• Activates Water Compaction each turn
• Activates Mercliess
• Transformed into Icy Field by Subzero Slammer
• Elemental Seed applies Soak and Aqua Ring, and poisons the user.

* -- Mountain 

• Activates Gale Wings during Strong Winds
• Pokemon with Long Reach deal x1.5 damage
• Transformed into a Snowy Mountain by Subzero Slammer
• Telluric Seed boosts Attack and lowers Accuracy

* -- Snowy Mountain 

• Activates Gale Wings during Strong Winds
• Pokemon with Long Reach deal x1.5 damage
• Activates Slush Rush
• Enables Aurora Veil
• Transformed into a Mountain by Inferno Overdrive
• Telluric Seed boosts Sp.Atk and lowers Accuracy

* -- Holy Field 

• Nature's Madness deals 66% HP damage (from 50%)
• Moongiest Beam, Sunsteel Strike, Prismatic Laser and Fleur Cannon damage increased x1.3
• RKS System's type becomes Dark at all times
• Never-ending Nightmare damage decreased x0.5
• Magical Seed boosts Sp.Atk and applies Magic Coat to the user

* -- Mirror Arena 

• Critical hits no longer deal extra damage and consume buffs
• Evasion no longer decreases when Pokemon are hurt in confusion
• Enables Aurora Veil
• Aurora Veil lasts 8 turns and boosts Evasion on use
• Moongeist Beam and Fleur Cannon damage doubles when reflected
• Prismatic Laser never misses and damage increases x1.5
• Destroyed by Tectonic Rage, causing Shatter damage
• Synthetic Seed boosts Evasion two stages

* -- Fairy Tale Field 

• Sparkling Aria, Solar Blade, Smart Strike, Moongeist Beam, and Fleur Cannon damage increased x1.5
• Floral Healing heals 2/3s target's HP (from 1/2)
• Pokemon with Queenly Majesty deal x1.5 damage
• Soul Heart additionally boosts Sp. Def on use
• Power of Alchemy Pokemon take x0.5 reduced Damage
• Magical Seed boosts Attack and applies King's Shield to the user

* -- Dragon's Den

• Tectonic Rage and Continental Crush deal additional Fire-type damage
• Sparkling Aria and Oceanic Operetta count towards transforming into a Cave
• Transformed into a Cave by Subzero Slammer and Hydro Vortex
• Elemental Seed boosts Sp.Atk and applies Flash Fire boost to the user

* -- Flower Garden Field 

• Floral Healing heals 3/4ths target's HP (from 1/2) after Stage 3
• Fleur Cannon damage increased x1.5 after Stage 3
• Acid Downpour reduces the field to Stage 1
• Transformed into a Burning Field by Inferno Overdrive
• Bloom Doom grows field by 1 stage
• Synthetic Seed boosts Sp.Def and applies Ingrain to the user

* -- Starlight Arena 

• Enables Aurora Veil
• Solar Blade deals additional Fairy-type damage
• Moongiest Beam, Sunsteel Strike and Black Hole Eclipse damage increased x2S
• Shadow Shield Pokemon take x0.5 decreased damage
• Magical Seed boosts Sp Atk and applies Lunar Dance to the user

* -- New World 

• RKS System matches Multitype's effects, but is selected separately.
• Core Enforcer, Fleur Cannon, Prismatic Laser, Sunsteel Strike, Spectral thief, Moongeist Beam, Multiattack and Continental Crush damage increased x1.5
• Nature's Madness deals 75% HP damage (from 50%)
• Shadow Shield Pokemon take x0.5 decreased damage
• Black Hole Eclipse damage increases x4
• Magical Seed boosts all stats and makes the user recharge

* -- Inverse Field 

• Magical Seed boosts all stats and makes the user recharge

* -- Psychic Terrain

• Priority attacks fail on grounded Pokemon
• Grounded Pokemon's Psychic attacks deal x1.5 increased damage
• Hex, Magical Leaf, Mystical Fire, Moonblast and Aura Sphere damage increased x1.5
• Pure Power doubles Sp.Atk instead of Atk
• Anticipation boosts Sp.Atk on switch in
• Telepathy Pokemon's Speed doubles
• The effect of the following stat-altering moves is increased:
• Nasty Plot Calm Mind Comsic Power Meditate
• Kinesis
• Psych Up, Meditate, Mind Reader and Miracle Eye additionally boost Sp.Atk two stages on use
• Hypnosis' accuracy is increased to 90
• Kinesis additionally lowers its target's Attack and Sp.Atk two stages
• Telekinesis additional lowers its target's Defense and Sp.Def two stages
• Gravity, Trick Room, Magic Room and Wonder Room last 8 turns
• Shattered Psyche additionally confuses its target
• Created by Psychic Terrain, Psychic Surge and Genesis Super Nova
• Secret Power may confuse its target
• Nature Power becomes Psychic
• Camouflage becomes Psychic
• Magical Seed boosts Sp.Def and Sp.Atk and confuses the user