In this fanfiction, it could be that Ash has a really good strategy. He might first make Gyarados use up a lot of its energy by making it attack Charmander's illusions or decoys. Then, when Gyarados is tired, Charmander can step in with its full power. Charmander could also use the environment to its advantage. Maybe there are some flammable objects around that can be set on fire by Charmander, creating a more powerful and widespread fire attack that Gyarados can't avoid.
The unexpectedness of it. Gyarados is a very strong Pokémon, and seeing it being defeated by a Charmander, which is not as physically imposing, makes for an interesting read. It could also be that in the fanfiction, there are unique twists and turns in the battle. For example, Charmander might discover a new move during the fight or Ash might come up with a last - minute strategy that turns the tables, all of which make the scenario really engaging.
A key element is the bond between Ash and Charmander. It's usually shown as a strong and unbreakable connection. Another is their growth. Ash grows as a trainer and Charmander as a Pokémon. For example, Charmander evolving into Charmeleon and then Charizard is often a big part of the story.
Ash's character development is quite significant. At first, he might be a bit over - eager and not fully understand Charmander's needs. But as they spend time together, he learns patience. He realizes that Charmander can't always be pushed to its limits right away. His confidence also builds. When they win battles together, he starts to believe in his own abilities more. And his sense of loyalty deepens as he would do anything to protect Charmander.
It could be about Ash finding a Gyarados in an unexpected place, like a hidden lake in a forest. Then he tries to train it and form a bond with it, facing challenges along the way.
You can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just type in 'Ash Gets a Gyarados' in the search bar and see what comes up.
One possible plot could be that Ash finds Charmander much earlier than in the original series. They could form a really strong bond quickly and start training in a different way. Maybe they focus more on speed and stealth rather than the usual battling approach at first.
One great fanfiction could be 'Ash as a Female: The Charmander Adventure'. It follows the female Ash as she embarks on her journey with Charmander. It's full of exciting battles and heart - warming moments between Ash and her Pokémon. The author does a great job of portraying Ash's determination in a new light.
I'm not sure of a specific 'ash defeats tobias fanfiction' off - hand. You could try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just type in the keywords 'ash defeats tobias' in their search bars, and you might find some great stories.