This is a page which will be updated (hopefully) every time a new character is introduced in both pasts. As such, it will involve both human, Elemental, and Pokémon characters both from Minami and from elsewhere. So without further ado: the characters from...
Yang: Also known as Sansol. Sister to Yin (a.k.a Trinyte). Legendary of Light. Tricked by Yin into staying on 'Traitor Island' at the time of the annual Elemental ceremony celebrated by every Pokémon on the main island. As it was Traitor Island to which the excess power is delegated, Yang was caught in the aftermath and the blast of power severed his Elemental link to Light. Filled with the rage of revenge, Yang absorbs the power the Guardian gives him in order to heal and then some, altering his physical form and ultimately disappointing the Guardian; who severs Yang's healed link deliberately this time to make him unable to attack his sister, and places a curse on him, changing him to Omneon. He is left on Traitor island, forbidden to return to the main island and turns to marble from dusk till dawn the next day.
As Omneon, he's still on Traitor Island when the human Trainer and his Pokémon arrive.
Yin: Also known as Trinyte. Brother to Yang (Sansol). Legendary of Darkness. Both Light and Dark legendaries scheme against each other - even though they're both halves to the whole - and it is ultimately Trinyte who gets the better of her brother first.
Attacks the Trainer on Traitor Island and is nearly caught by him before escaping.
The Guardian: A Minami Flora legendary (also a wielder of Aura) turned tree spirit after melding with the One Tree back when Minami had its first human visitors and becoming an entirely new creature; one not with a true physical form but whose Aura presence is yet still slightly visible. Has a powerful feeling of enmity against humans in general for most of the time due to its first encounter which... didn't go so well. After this, the Guardian becomes Minami's sworn protector against the more bloodthirsty race who live across the sea and whenever Minami's safety is threatened, the Guardian reacts in kind to the 'trespassers'.
Comes to the Trainer's rescue (possibly the only reason for this is because he is not on the main island) and pacifies the incensed Trinyte, then teleports the Trainer and his Pokeémon back to their home.
Unnamed Trainer: Owns a Lapras (Vanessa) and a Flareon (Farrell). Discovers Traitor Island - the most northerly island of Minami. Has a good relationship with his Pokémon, and this is recognised by the Guardian even when it does not fully understand how the relationship is meant to truly work.
Dirk: One of the new characters which somehow just started existing when I started rewriting 'The Guardian'. Dirk is a guy with a shrouded past - not even I know much about it. He travels around, exploring and surviving on the land with his son, Kris. He owns a Manetric called Strike and a horde of Tauros which pull his caravan around (the lead Tauros is called 'Bullet'). He's desperate to settle down and give Kris a good life - hopefully this is made pretty clear in the prose as well.
Kris: Dirk's son, eight years old. Given an Electrike puppy called Blink (which is Strike's child) by Dirk.