The small mouse can be caught pretty early on if you know where to look for it. It just multiplies as it evolves. In this Pokemon: Scarlet and Violet guide, we cover where you can find Tandemaus and how you can evolve it into Maushold.
Evolving Tandemaus Into Maushold In Pokemon: Scarlet And Violet
Tandemaus can be found in a couple of different locations but there are plenty on the route to the Pokemon League. The Pokedex says that it is rarely seen but that is not the case.
To Evolve Tandemaus into Maushold you need to level it up to 25. There is no evolution animation so it is just going to become a Maushold. There are two versions of Maushold according to data miners. There is a variant with a single child and another variant with two children. Which variant you get could be completely random. There is no way of knowing for sure at the time of writing. It seems that the variant with the single child is rarer.
This is how you can evolve Tandemaus into Maushold in Pokemon Scarlet and Violet. If you are interested in learning more then you can check out our guide on the exclusive Pokemon for each version of the game. You can also check out our guide on how you can get a free flying-type Pikachu.