This is probably really dumb and a bit of a long backstory, but I had these ideas for a Scandinavian Pokémon region, and I thought about what I wanted to do for legendaries. Life and death had already been done in X and Y. I'm not the best at drawing ideas out, but the idea I had was that I originally wanted to do the Aesir and Vanir, the main two tribes of gods in Norse mythology. I had the idea to make a Freyr horse and an Odin raven-griffin thing that was the original idea.

You see, the Aesir represent war, order, governance, technology, reason, and law, while the Vanir represent fertility, prosperity, nature, and magic. So I got the idea of Chaos vs. Order, since I think that's something Pokémon hasn’t done yet, or Freedom vs. Control.

The Aesir’s main adversaries are the Jotnar, who are generally thought of as frost giants but more broadly represent the chaos of nature—storms, earthquakes, floods—not just snowstorms. Chaos vs. order is a big theme in mythology. If you’ve ever heard of the chaoskampf, there’s usually a sky-patriarch god that fights against a dragon or snake, representing order fighting chaos: Marduk vs. Tiamat, Thor vs. Jormungandr, Zeus vs. Typhon, Indra vs. Vritra—it’s all over the place.

I got the idea to make one of the legendaries based on the Vanir and Jotnar, particularly Freyr and Loki, and the other one based on the Aesir, particularly Odin. I decided I wanted them to have names you could put in a Pokémon title, so I thought Key would work well for freedom and Lock would work well for order. So Pokémon Key and Pokémon Lock, or vice versa, however suits your fancy.

I decided the Key one would be a Fairy/Dark legendary representing magic, passion, nature, chaos, and freedom, and the Lock one would be a Steel/Psychic legendary representing technology, reason, civilization, order, and control. I also decided to give them pre-evolutions that would each evolve into their final form, just because I thought it’d be interesting similar to Cosmog, except each gets their own pre-evo.

I decided the third legendary would be primarily based on Ratatoskr as a messenger-like Pokémon, but also partly based on Yggdrasil and the Vanir, since I gave some of their role to the Jotnar. It would represent balance, or equilibrium, between chaos and order.

Brelequs Line (Key Legendary)

1st form: Brelequs – Fairy/Ghost, based on a baby horse, fertility rituals connected to Freyr, and Loki being able to transform into a horse. Has a small horn.

• Name origin: Brellu (Icelandic for “trick”) + equus (Latin for horse)
• HP: 90
• Attack: 125
• Defense: 60
• Sp. Attack: 85
• Sp. Defense: 120
• Speed: 110
• BST: 590

2nd form: Brellubellis – Fairy/Dark, based on a horse, Sleipnir, Blodughófi, and a Qilin (horn shaped like a key). Nature-inspired.

• Name origin: Brellu (Icelandic for “trick”) + Rebellis (Latin for “rebel”)
• HP: 100
• Attack: 140
• Defense: 80
• Sp. Attack: 102
• Sp. Defense: 138
• Speed: 130
• BST: 690
• Ability: Liberation – Doubles all stat increases made by the user's team and any stat increases the user makes going forward while the Pokémon is on the battlefield. think simple but only boosts and i effects both the users pokemon in double battles and change any stat increases already made
• Signature Move: Spirit Saber – 65 BP Fairy Physical. Manifests a blade of spiritual energy that targets the spirit, bypassing anything restricting its power. Always hits a critical, removes Protect, and removes screens.

Odiphus Line (Lock Legendary)

1st form: Odiphus – Steel/Flying, based on a baby raven and a griffin, as well as Huginn and Muninn. Large wings.

• HP: 100
• Attack: 80
• Defense: 120
• Sp. Attack: 115
• Sp. Defense: 85
• Speed: 90
• BST: 590

2nd form: Odominus – Steel/Psychic, based on Odin, a raven, griffins, and owlbears, as well as Huginn and Muninn. Wings form a lock shape.

• Name origin: Odin + Dominus (Latin for lord or master)
• HP: 125
• Attack: 93
• Defense: 135
• Sp. Attack: 130
• Sp. Defense: 97
• Speed: 110
• BST: 690
• Ability: Solemn Decree – Nullifies all stat increases from the opposing team and prevents opposing Pokémon from raising their stats.
• Signature Move: Divine Order – 90 BP Steel Special. Calls down divine light to smite a foe and restrict an opponent. Prevents the opponent from switching out and prevents them from using the same move next turn. Hits two opponents.

Raostium Line (Third Legendary)

1st form: Ratostium – Grass/Fighting, based on the Vanir and Ratatoskr, keeps the peace between factions and Yggdrasil itself.

• Name origin: Ratatoskr + Ostium (Latin for door)
• HP: 160
• Attack: 70
• Defense: 70
• Sp. Attack: 70
• Sp. Defense: 70
• Speed: 160
• BST: 600

2nd form: Realmtoskr – Grass/Fighting, based on the Vanir and Ratatoskr, keeps the peace between factions, Heimdall, and Yggdrasil itself.

• Name origin: Ratatoskr + Realm
• HP: 140
• Attack: 100
• Defense: 115
• Sp. Attack: 90
• Sp. Defense: 115
• Speed: 140
• BST: 700
• Ability: Equalizer – Reacts to stat changes and acts accordingly. For example: if an opponent's Attack is boosted, the user's Defense sharply rises. If an opponent's Defense is boosted, the user's Attack sharply rises. The effect applies to all Pokémon on the field but does not stack per use.

Inversely, if the user's stats are lowered, the corresponding stats of the opponent are sharply lowered. For example:

• If you lower my Defense, both of your Pokémon’s Attack stats are sharply lowered.
• If you lower Speed, both of your Pokémon’s Speed stats are sharply lowered.
• If you lower Special Attack, both of your Pokémon’s Special Defense stats are sharply lowered.

Similarly, if the opponenet's stats are raised, the corresponding stats of the user's Pokémon are sharply raised:

• If you raise Speed, both of my Pokémon’s Speed stats are sharply raised.
• If you raise Defense, both of my Pokémon’s Attack stats are sharply raised.

It’s a complex effect but effectively mirrors and counters stat changes between sides. I decided it shouldn't stack because then it might get too confusing to keep track of

• Signature Move: Homeostasis – Fighting Status, 2-turn move. User absorbs energy, heals ¼ of max HP, and raises Attack, Defense, Sp. Attack, Sp. Defense, and Speed on the next turn. Similar to Geomancy, but raises every stat and heals only 1 stage.

Steel > Fairy
Dark > Psychic 
Fighting > Dark
Fighting > Steel 
Fairy > Fighting
Psychic > fighting

Anyway these are very rough ideas i had but i just wanted to hear other people's thoughts