Gym 1 Olivia (Grass, Olive=Olive Tree)
-The battle would take place in a forest and Olivia would have bonded with Virizion and use it in battle. She would be very calm minded but refuses to leave the forests and wildlife as she hates the suburbs and non-plant land. The test of this gym battle is working with nature where Noctowl flies through the trees and hides at the tops, Pignite uses rollout off them for a few wins and Tortera uses synthesis like the trees, uses rock climb to move the land and eats another energy ball to give itself a larger boost. This match is basically where Torterra gets redemption by defeating Virizion and learning Rock Polish (Probably won't happen, but just a general wish). The test in this gym match would be to fulfill the pokemon's wishes in battle and to use it's faith to win (Ash would see Torterra wants to be speedy, and helps it learn rock polish for a rematch).
Gym 2 Edgar (Dark, Edgar is an old unique name)
-Edgar is a bit of a mystery, he has a rivalry with Madam Rouge of the third gym because of her snobbish personality and he always pretends to be of a high class to try to look better than her. In reality, this is all an illusion and is fairly poor but cares for his pokemon deeply. His signature pokemon is Zoroark and it causes Ash a lot of problems in battles, who tries to use pokemon that care for him a lot like Kingler and Bayleef to show pokemon can love their trainers to Edgar, who is pretending to be like Madam Rouge. The battle ends with Krookodile defeating Zoroark with faint attack, with ash remarking that Edgar isn't the only guy who can play sneaky. This battle would be a test of cunning and prediction, Ash would have to watch Edgar's pokemon to see whether they are real or are Zoroark in disguise. Ash would use this similarly on his pokemon like with Krookodile where it would pretend to use moves like thunderfang and dig, but would actually use faint attack to suprise Edgar.
Gym 3 Madam Rouge (Pyschic, has to be something unusual)
-Madam Rouge would be this really snobbish lady who would look down at some species of pokemon and would have been brought up in a really rich family that would have given her special lessons at an early age of pokemon. She would spend her life bonding with her pokemon and learning how to be in-synche with them and decide when they will feel tired even before they feel it. She looks down at some of Ash's pokemon, calling them common and questions as to whether Ash's pokemon love him enough to win the battle. The test of this battle would be working in-synche with your pokemon and trying to work with them so perfectly, you would be able to guess when they would be tired and when they are winning or losing the battle. Ash learns this by watching Swellow and making sure it isn't flying too close to the ground as a sign of tiredness and watching the speed of Tauros to see whether it is going too slow or not. Seismitoad stars here as a swampy pokemon that disgusts Madam Rouge and wins the battle with Ash giving Seismitoad enough faith to pull off a hyper voice-hydro pump combo to win.
Gym 4 Magnus (Steel gym, 'magn'=Magnet)
-Magnus would be a researcher/train station manager who wouldn't show affection towards his pokemon and would be very calculated in his battling style. To show what faith and love means, Ash uses pokemon like Torkoal who once feared steel types, Buizel who love to battle and don't care about looking childish through affection and as a suprise, Scraggy who actually evolves here because of Ash's faith and to Magnus's suprise who believed there was no experience points that could have caused Scraggy to evolve. The test of this gym battle would be calculation where Ash would have to decide how much damage each of his pokemon's moves would do, and how much health each members of his team have.
Gym 5 Shade (Ghost type, Shade=Dark, gives off bad impression)
-Shade was the original gymleader of the gym until one of his friends started spreading rumours that he was a criminal and made him look like a bad guy. Ash and Co. help expose this and he returns to his gym post. His backstory is supposed to reflect how some ghosts are misunderstood (A clear one being Casper). He is a very clear-minded and open person, and is a large threat for Ash. The test of this battle is endurance as Shade's ghost pokemon use moves such as will o wisp and toxic, and Ash has to increase his pokemon willpower to win the battle. At first, Dewott is scared of Banette and Golurk, but manages to be brave enought to beat them.
Gym 6 Romilda (Poison, the rockstar girl, romilda just sonds venomous to me)
-Romilda is the daughter of a former legendary gymleader who wishes for her to take his title of gymleader. But she doesn't want to and wants to be a rockstar with her friends. The two start fighting and after some help from Ash and Co., Romilda decides to be both and Cilan tells the original gymleader that blood doesn't make the gymleader but the skill and he decides that when Romilda is away, he will appoint his nephew to be gymleader and will teach him. The battle ends with Snivy acting like a boss and learning twister to destroy Roserade's poisonous attacks like poisonpowder.
Gym 7 Terrence (Rock, Terra is latin for ground, I know it is rock, but still)
-Terrence is a fairly old man who grew up in a city that was similar to white city and now a large group of developers have come to turn it into an industry. Terrence is against this idea, and starts protesting stating that the land for the pokemon should be more important. After the whole mishap and in the actual battle, Ash is thrown by suprise with Rhyperior as he thought Terrence only had fossil pokemon. Terrence is fairly bitter and is shown to resent society as they are ignorant to pokemon's wishes and states he only battles if his pokemon want to. He suggests near the end of the battle that Ash is pushing his pokemon too hard and this reveals the test of this gym battle: Limits. Ash learns this by having Muk used only for taking hits, Sceptile for speedy-hard hitting attacks and Boldore for the finishing blows. Terrence admires this and gladly gives Ash his gym badge.
Gym 8 Artie (Water gym, based on the character from the manga scans. Artie is derived from Arthur which is the first name of Aquaman. Go ahead and sue me, I can't think of anything )
-Artie is a part lifeguard-gym leader and is the most powerful of the gym leaders in the filler saga region. He feels pressured with the title of being the strongest gym leader as he feels he has to look strong and bold all the time but just wants to have fun and be calm about anything. But when he combines the feelings of saving someone in the lifeguard business to pokemon battling, he becomes a formidable threat. Ash's Totodile amuses him and he even asks for a trade, but Ash refuses. The battle takes place on a beach and the test of this gym battle is taking control of multiple situations that are thrown at you before they get out of hand. It is a double battle and it gets intense with Kingdra creating a large whirlpool and Ludicolo using blizzard everywhere as Staraptor evades by hiding in the air, and Heracross tries to cover itself with it's arms. Eventually the two pokemon learn to use their enemies to their advantage, by accidentally causing Ludicolo to freeze the whirlpools and for Staraptor to use brave bird onto Ludicolo to push him into it and Heracross takes out Kingdra with focus punch. The battle is won and Ash first acts really happy for winning all eight gyms, but Artie tells him that the final battle awaits, with the ringleader of the entire gyms who will be faced after the league. It is a smaller version of the unova league with characters like Trip and Ash competing to battle the big champion. Ash wins and gets to face him
Champion Battle Draco (His signature pokemon is dragon, tried to make things interesting...)
-Draco is the legendary leader of the special eight gyms of eastern unova/filler region, and he sets high standards for his competitors so he can feel as though he has a challenge. He is apparently very famous though Ash has never heard of him and he always tries to anger his competitors so they get more motivated for their battles. In person he seems like a douche, but it is all intented so the likes of Ash can use their true power. The battle starts with great difficulty as Ash has to switch between all of his pokemon to just defeat Thundurus, but it is up to Pikachu to defeat it. Each member of the team defeat their type opposites after great difficulty and the final match is Gabite vs Hydreigon. It is insanely difficult as Hydreigon abuses ice beam, causing Gabite to run for it's life. Hydreigon stops and uses outrage a lot which destroys most of the stadium. Draco reveals the test of this battle: Trust. Ash looks to Gabite who struggles but is motivated and a redish aura starts to surround all of it's body, particularly it's eyes. It then looks to Ash with a smirk and then Ash smirks, realising what is happening. Draco is intrigued and smiles, but orders Hydreigon to finish it off with outrage, but Gabite fights back with it's own outrage (Tutor move in B2W2). It is a long match and both pokemon are tired, but Gabite finishes the match in a humurous way similar to what it did as a Gible and bites onto one of Hydreigons armish heads and unleashes the first used draco meteor in the match, both suprising Draco and amusing Ash. Hydreigon is out and Ash is declared the winner. Ash wins the champions league and brags to Trip about how he is the champion of the pokemon league, but Trip mutters that since the gyms weren't officially set up, the league is only a test and not official. Ash is startled by this, but after getting a trophy to show his recognition as the champion, he smiles and returns to Pallet Town.