Where could you teach your Gyaradose mimic in soul silver?

You can't teach a Gyarados Mimic in Soul Silver. Mimic is a move that is only learned by certain Pokémon in the Generation 2 games, and Gyarados is not one of them.

Here's why:

* Mimic's Availability: In Generation 2, Mimic is only learned by the following Pokémon:

* Staryu: Learns it at level 1.

* Starmie: Learns it at level 1.

* Scyther: Learns it at level 1.

* Scizor: Learns it at level 1.

* Smeargle: Learns it by default.

* Gyarados's Movepool: Gyarados does not learn Mimic through leveling up, breeding, or any other method in Soul Silver.

Possible Misunderstanding: You might be thinking about the move Copycat which was introduced in Generation 4 (Diamond/Pearl). This move can be learned by some Pokémon including Gyarados, but it's not available in Soul Silver.

Let me know if you have any other questions!