It is always interesting when you find a Pokémon that seems to completely go against all preconceptions about how types usually work in the games. Tynamo and its evolutionary line is definitely one of these Pokémon, being a fish creature that is purely an Electric type. This makes it lethal against other Pokémon in its natural environment, but you will need to know where to look to add it to your party. Here is where you can find and catch Tynamo in Pokémon Scarlet and Violet.
How to catch Tynamo in Pokémon Scarlet and Violet
To find Tynamo in Pokémon Scarlet and Violet, you are going to need your Koraidon or Miraidon to be able to swim by defeating the Open Sky Titan Pokémon. After that, you can jump into bodies of water and start battles with Pokémon that were previously inaccessible.
Tynamo are located in the sea all along the northern and western Paldea seas. There are also a couple of rivers you can go to near these areas to find them, but most commonly, you will find them in the larger open waters. They can appear during the day or nighttime and do not run away when they notice you. They can occasionally be seen swimming alongside an Eelektrik.
When you begin a battle with the Tynamo, it naturally would be susceptible to Ground attacks since it is an Electric Pokémon, but it has the Levitate ability, which makes it avoid them. It is resistant to Electric, Flying, and Steel moves, so avoid those as well. Hit it with any other kind of attack to make it easier to catch.
After you catch Tynamo, you can have it evolve into Eelektrik by raising it to level 39. From there, you will need a Thunder Stone to evolve it into the final form, Eelektross.