Nintendo Australia today provided details on how to obtain Serperior, Emboar and Samurott in Pokémon Omega Ruby and Alpha Sapphire.
Today on Pokemon.com, a code for the Grass-type Serperior will be available. Then, from tomorrow, a code for Emboar will be available on the same site.
Getting Samurott requires a subscription to the Pokémon Trainer Club newsletter, which can be obtained by signing up here. The February newsletter contains said code, so you’ll need to sign up before 31 January.
The codes can be redeemed any time before 30 November.