Middle the area if you didn't get it at the Generator Chamber
Pokémon
During chapter 2 story within the laboratory, a Mime Jr. can be found in the capsules room.
After acquiring the HQ Railnet Key from Valor Mountain, the Player can take the Rails at the Helojak Factory Hidden Cove to the Hidden Lab, there will be a capsule machine with an intractable slot, when inserting three Cell Batteries, one Metal Powder, and one Pokéball it will dispense a Pokéball with a Ralts in, it knows the move Shadow Sneak.