For Munchlax there's a trade in Calcenon that allows you to trade a Qwilfish for Munchlax with an NPC is the PokeCenter.
For Corsola it can be found either at Apophyll Beach during a Thunderstorm (need Pokesnax), or rare find if you dive under Azurine Lake.
Shuppet can be found at Beryl Ward at night.
Gothita can be found in the Beryl Library by talking to one of them.
Eeletrik can also be found in Azurine Lake with dive.
And Bounsweet can be obtained in a quest where you show the lady who gives you the Soothe Bell a Glameow you got from the other hair grooming place and her reward for beating her is Bounsweet if you can't find the rest of these or if you really wan't to trade then just contact me and I'll trade you them.