Many pokemon have an 'alternate' typing, rather than the one their specie would normally have. This can be because of many things, such as environment changes or specie heritage.
This is the list of Deltas that have been found so far.

Charmander/Charmeleon/Charizard

(For Charizard, )
Moveset changes:
Smokescreen --> Thunder Wave
Scary Face --> Dragon Dance
Fire Spin --> Twister
Flare Blitz --> Outrage

Notes: Still need tail flame to live.

Sandshrew/Sandslash
Delta:
Moveset changes:
Defense Curl -> Iron Defense
Poison Sting -> Spikes
Rollout -> Bullet Punch
Fury Cutter -> Metal Claw
Sand Tomb -> Magnet Bomb
Weak/Resist: Weak to fire, resists grass. All others remain.)

Nidoran:f:/Nidorina/Nidoqueen
Delta:
(Nidoqueen )
Moveset changes:
Poison Sting -> Bubble
Toxic Spikes -> Water Sport
Crunch -> Waterfall
Poison Fang -> Brine
Earth Power -> Surf
Superpower -> Hydro Pump
Weak/Resist: Resists Water.
Abilities: Rivalry/Water Absorb
Physical: Deltas are much lighter, and built a bit more suited for the water. In rare cases, small, underdeveloped fins have been found.

Nidoran:M:/Nidorino/Nidoking
Delta:
(Nidoking )
Moveset Changes:
Peck -> Rock Smash
Poison Sting -> Seismic Toss
Toxic Spikes -> Bulk Up
Poison Jab -> Submission
Thrash -> Sky Uppercut
Megahorn -> Superpower
Abilities: Rivalry/Guts

Vulpix/Ninetales
Delta:
Ember -> Confusion
Roar -> Teleport
Will-o-Wisp -> Secret Power
Flame Thrower -> Future Sight
Payback -> Psychic
Fire Spin -> Miracle Eye
Fire Blast -> Psycho Boost
Nasty Plot -> Hypnosis
Ability: Serene Grace

Meowth/Persian
Delta:
Moveset Changes:
Lv 14 Screetch
Lv 17 Fury Swipes -> Dark Pulse

Geodude/Graveler/Golem
Delta:
Mud Sport -> Bulk Up
Magnitude -> Reversal
Earthquake -> Superpower

Slowpoke/Slowbro/Slowking
Delta: Requires a Delta Shelder ()
Moveset Changes: (only after evo, Slowpoke does not get these)
Water Gun -> Thundershock
Water Pulse -> Thunderbolt
Withdraw -> Thunder Wave
Psych Up -> Thunder

Shellder/Cloyster
Evolution: IF Delta, requires Thunder rather than Water stone.
Delta:
(for Cloyster, )
Moveset changes:
Withdraw -> Charge
Clamp -> Thunder Fang (uses shell like a mouth)
Whirlpool -> Thunder Wave
Brine -> Thunderbolt

Voltorb/Electrode
Delta:
Charge -> Iron Defense
Spark -> Iron Head
Screech -> Metal Sound
Charge Beam -> Flash Cannon

Magikarp/Gyarados
Delta:
No changes to moveset, only STAB

Mewtwo
Delta: Any and all, due to genetic instability.
No Moveset Changes, only STAB

Mew
Delta: Any and all, due to their transform ability and having a permanent body, unlike Ditto.
No Moveset Changes, only STAB

Cyndaquil/Quilava/Typhlosion
Delta:
Moveset Changes:
Ember -> Pursuit
Smokescreen -> Fake Tears
Flame Wheel -> Bite
Lava Plume -> Dark Pulse
Flamethrower -> Shadow Ball
Rollout -> Night Slash
Eruption -> Shadow Force
Ability: Super Luck

Bonsly/Sudowoodo
Delta:
Rock Throw -> Vine Whip
Rock Tomb -> Razor Leaf
Rock Slide -> Energy Ball

-TBC-