Pokemon Location

Where can find the following Pokemon in the game?

1. S51
2. Antarki
3. Duplicat
4. Praseopunk
5. Sheebit
6. Volchik
7. Lavent

1. From a sidequest, don´t know the exact location on where to start.
2. Can´t be obtained yet.
3. In the labyrinth cave on Maskara island.
4 + 5 + 6 + 7. Can´t be obtained yet.

Moved to General Discussion since it doesn't have to do with a glitch or error.

S51 can be obtained by doing a sidequest in the Wheatfields outside Vinoville, and must be done at night. There is a point of no return after beating the gym, so do this BEFORE fighting the gym leader.

And with the question answered (thanks Stuiterbal for covering the rest), thread locked.