Below are the synergies. Thanks to Ribbonchu for the translations. I have included the screenshots and some brief notes for each type.
Elemental Weakness
Pokemon Unite auto chess does not have elemental weakness. Therefore, going water to counter fire types is not a strategy that can be used.
Behemoth

Behemoth Pokemon:
- Snorlax
Snorlax is able to tank like a pro and a nice swap if you lack a tank mid to late game.
Dark

Dark Pokemon reduces the offenses and defenses of opponents, and the more Pokemon they knock out, the stronger their offenses.
- x2 – Reduce the opponent’s ATK and SP ATK by 5%, and DEF by 30.
- x3 – Reduce the opponent’s ATK and SP ATK by 7%, and their DEF and SP DEF by 90.
- x4 – Reduce the opponent’s ATK and SP ATK by 10%, and their DEF and SP DEF by 40%+120.
- X5 – Increase DEF and SP DEF reduction to 50%+120.

When an opponent is knocked out, gain one Fear Aura stack. Only Dark Pokemon can benefit from the effects of Fear Aura.
- x5 – Increase ATK by 5%.
- x15 – Increase ATK by 10%.
- x25 – Increase ATK by 18%.
- x40 – Increase ATK by 28%
- x60 – Increase ATK by 40%.
Dark Pokemon:
- Zorua / Zoroark
- Umbreon
- Absol
- Tyranitar
Dark Pokemon early game is hard to build up the fear aura, but mid to late game, it is very strong when you have better Pokemon to support it. Unfortunately, Zorua is a really, really bad Pokemon, so it’s hard for it to knock anything out. Umbreon is an amazing tank and not great for knocking out Pokemon. It isn’t until you have Absol that you can more easily build your fear aura.
Dragon

Dragon Pokemon increase their ATK SPD.
- X2 – +10% ATK SPD.
Dragon Pokemon:
- Dragonite
- Miraidon
Dragonite with Unite disk is an incredible carry, so that dragon alone can carry without Miraidon.
Elusive

Elusive Pokemon gains increased special attack.
- x1 – +15% SP ATK
Elusive Pokemon:
- Gengar
Gengar with the proper item and Unite disk can also carry a team.
Evee

Star Eevee units gain unique buffs that all stack with each other. More
Eeveelutions means More Star Power!
- x2 – +10% Damage.
- x3 – AND +10% Damage Reduction.
- x4 – AND gain 6 Move Progress when dealing normal attack damage.
- x5 – AND +35% Move Damage.
- x6 – AND when using a move, a meteor will spawn and attack a random opponent.
Evee Pokemon:
- Umbreon
- Leafeon
- Espeon
- Sylveon
- Glaceon
An Evee chip is required for the meteor. It is flashy but not enough to solo carry (unfortunately).
Electric

Electric Pokemon deal “Electric Shocks”, additional damage after they deal a certain number of damage instances.
- x2 – After 6 instances of damage, cause one Electric Shock.
- x3 – After 3 instances of damage, cause one Electric Shock.
Electric Pokemon:
- Pikachu
- Zeraora
- Zapdos
- Miraidon
It is easy to hit the max level for electric, since there are more electric types than needed. As a result, even at x3, the Electric Shock isn’t going to carry you. Zapdos with the Unite disk is the carry on this composition.
Fairy

Fairy Pokemon summon Zacian to the field as an ally. Its strength is dependent on the number of Fairy Pokemon in play.
- x2 – Summons Zacian. (1 Star)
- x3 – Summons Zacian. (2 Star, uses Metal Claw as a move.)
- x4 – Summons Zacian. (2 star, uses Metal Claw as a move.)
- x5 – Summons Zacian. (3 star, uses Metal Claw as a move, has Drain Crown equipped.)
- x6 – Summons Zacian. (3 star, uses Metal Claw as a move, has Drain Crown and Technical Machine equipped to use Behemoth Blade as a special move.)
Fairy Pokemon:
- Jigglypuff / Wigglytuff
- Mr. Mime
- Sylveon
- Clefable
The summon adds an extra unit and can deal a bunch of damage. Strong for early and mid game. You need 2 fairy chips to get to max, which is hard to get.
Fighting

Fighting Pokemon absorbs physical strength when causing damage, and each normal attack will increase their attack speed.
- x2 – +10% Lifesteal. ATK SPD increases by 10% after each normal attack.
- x3 – +20% Lifesteal. ATK SPD increases by 15% after each normal attack.
- x4 – +30% HP regeneration. ATK SPD increases by 20% after each normal attack.
- x5 – +45% Lifesteal. ATK SPD no longer increases, but +280% normal attack damage.
- x6 – Steal 45% of target’s ATK. Normal attacks deal extremely high damage in an large area.
Fighting Pokemon:
- Machop / Machoke / Machamp
- Lucario
- Kubfu / Urshifu
Getting life steal is very nice for survivability. Urshifu is the carry with the Unite disk.
Fire

Fire Pokemon apply a damage-over-time debuff that is a fixed number equal
to 1% of the opponent’s Maximum HP per second and reduce healing
effects by 30%.
- x2 – This damage is increased by 6%
- x3 – This damage is increased by 16%
- x4 – This damage is increased by 24%.
- x5 – This damage is increased by 36%. This debuff cannot be
cleansed. - x6 – This damage is increased by 50%. This debuff cannot be
cleansed. Affected targets deal 70% less damage.
Fire Pokemon:
- Charmander / Charmeleon / Charizard
- Fennekin / Braixen / Delphox
- Scorbunny / Raboot / Cinderace
Fire used to be very strong, and it seems like hitting the max with 3 fire chips is nearly impossible.
Ice Pokemon will apply a “Frost” effect to opponents that hit them with
normal attacks. They will be frozen once every 10 instances.
- x2 – Each Frost stack adds 2% extra damage
- x3 – Each Frost stack adds 4% extra damage
- x4 – Each Frost stack adds 8% extra damage and gain 120 DEF/ SP
DEF - x5 – Summons Articuno after 10 seconds
Grass

Grass Pokemon restore HP every 3 seconds. Defeated allies grant stacks of New Green when knocked out. Grass Pokemon grant an additional stack.
- x2 – Restore 2% HP every 3 seconds. Gain 2 stacks of New Green upon ally KO.
- x3 – Restore 3% HP every 3 seconds. Gain 3 stacks of New Green upon ally KO.
- x4 – Restore 4% HP every 3 seconds. Gain 4 stacks of New Green upon ally KO.
- x5 – Restore 5% HP every 3 seconds. Gain 5 stacks of New Green upon ally KO.
- X6 – Restore 6% HP every 3 seconds. Gain 6 stacks of New Green upon ally KO.

When the total number of New Green stacks reaches certain breakpoints, they can be consumed for prizes
- x10 – Can be exchanged for 1 common reward.
- x40 – Can be exchanged for 1 uncommon reward.
- x80 – Can be exchanged for 1 rare reward.
- x120 – Can be exchanged for 2 rare rewards.
- X180 – Can be exchanged 3 super rare rewards.
Grass Pokemon:
- Rowlet / Dartrix / Decidueye
- Bulbasaur
- Leafeon
- Steenee / Tsareena
- Gossifleur / Eldegoss
Grass is great to start building up the New Green stacks early. It isn’t good to start investing in grass mid to late game, since the game will be over before you can take advantage of the rare rewards.
Ice

Ice Pokemon will apply a “Frost” effect to opponents that hit them with normal attacks. They will be frozen once every 10 instances.
- x2 – Each Frost stack adds 2% extra damage
- x3 – Each Frost stack adds 4% extra damage
- x4 – Each Frost stack adds 8% extra damage and gain 120 DEF/ SP DEF
- x5 – Summons Articuno after 10 seconds
Ice Pokemon:
- Swinub / Piloswine / Mamoswine
- Vulpix / Alolan Ninetale
- Lapras
- Glaceon
Summoning an Articuno after 10 seconds is lots of fun. But ice isn’t very strong right now, so seeing that legendary Pokemon isn’t going to win you games.
Psychic

Psychic Pokemon recover a certain amount of Move Progress per second.
- x2 – Restore 4 points of Move Progress per second.
- x3 – Restore 6 points of Move Progress per second.
- x4 – Restore 8 points of Move Progress per second.
- x5 – Restore 10 8 points of Move Progress per second. Start battle
with full Move Progress. - x6 – Each time a move is used, it’s damage is increased by 30 20%.
Psychic Pokemon:
- Ralts / Kirlia / Gardevoir
- Fennekin / Braixen / Delphox
- Mr. Mime
- Espeon
- Mewtwo
Move means the requirement before casting your special move. As a result, the faster your move progress is, the faster you can cast your special move. At x5, full move progress allows for some crazy burst.
Water

Water Pokemon attract “huge waves” that move towards the opponent.
- x2 – Increase ATK and SP ATK by 10%
- x3 – Increase ATK and SP ATK by 20%
- x4 – Increase DEF AND SP DEF by 120.
- x5 – “Huge waves” will spawn occasionally that deal damage to
enemies - x6 – “Huge waves” deal more damage and cleanse hindrances for
allies
Water Pokemon:
- Psyduck
- Cramorant
- Squirtle / Wartortle / Blastoise
- Froakie / Frogadier / Greninja
- Lapras
- Sobble / Drizzile / Inteleon
You can get x6 without any water chips, which is great. You can collect these from early to mid game without any problems.
Rock

Rock Pokemon increase their defenses.
- x2 – +280 SP DEF.
Rock Pokemon:
- Dwebble / Crustle
- Tyranitar
Due to the big difference in 1 and 4 cost, this synergy is hard to get. You’re most likely using Tranitar for the dark synergy and just using Dwebble early on as a tank.
Burst
Burst Pokemon increase their move damage.
- x2 – +10% Move Damage.
- x3 – +20% Move Damage.
- x4 – +40% Move Damage.
Guardian

Guardian Pokemon gain increased defenses.
- x2 – +90 DEF and SP DEF.
- x3 – +180 DEF and SP DEF.
- x4 – +360 DEF and SP DEF
Guardian Pokemon:
- Dwebble / Crustle
- Swinub / Piloswine / Mamoswine
- Squirtle / Wartortle / Blastoise
- Mr. Mime
- Gossifleur / Eldegoss
- Snorlax
Offensive

Offensive Pokemon increase their physical strength.
- x2 – +10% ATK.
- x3 – +20% ATK.
- x4 – +40% ATK.
Offensive Pokemon:
- Rowlet / Dartrix / Decidueye
- Lucario
- Froakie / Frogadier / Greninja
- Steenee / Tsareena
- Dragonite
Skilled

Skilled Pokemon increase their special attack.
- x2 – +10% SP ATK.
- x3 – +20% SP ATK.
- x4 – +40% SP ATK.
Skilled Pokemon:
- Ralts / Kirlia / Gardevoir
- Pikachu
- Vulpix / Alolan Ninetale
- Espeon
- Zapdos
Speedy

Speedy Pokemon increase their attack speed.
- x2 – +10% ATK SPD.
- x3 – +20% ATK SPD.
- x4 – +40% ATK SPD.
Speedy Pokemon:
- Zorua / Zoroark
- Cramorant
- Scorbunny / Raboot / Cinderace
- Zeraora
- Absol
Support

Support Pokemon increase their HP.
- x2 – +10% HP.
- x3 – +20% HP.
- x4 – +40% HP.
Support Pokemon:
- Psyduck
- Jigglypuff / Wigglytuff
- Umbreon
- Lapras
- Clefable
Universal

Universal Pokemon gain increased damage and damage reduction.
- x2 – +5% Damage and Damage Reduction.
- x3 – +10% Damage and Damage Reduction.
- x4 – +20% Damage and Damage Reduction.
Universal Pokemon:
- Machop / Machoke / Machamp
- Charmander / Charmeleon / Charizard
- Leafeon
- Kubfu / Urshifu
- Tyranitar
- Meowtwo
Conclusion
That is all, I hope you have a good overview of the different synergies in Pokemon Unite Auto Chess. You won’t always get the synergies you want, so you need to do the best with what you have. Especially when it comes to chips, that can really make or break your games. Just keep your composition flexible to ensure whatever randomness can be properly dealt with.