Inverse Battle
Once a day, you can head to special Inverse Battle Hall located in Mauville City and battle Inver, who you can challenge to an Inverse battle (duh)
Rotation Battle ## - Thanks to V on this one
After you have access to Mauville Hills, you can find an Old Woman who you can challenge to a Rotation Battle once a day
Secret Base Trainers## - Thanks to V on this too
You may battle your Secret Base Buddies once a day, who are located at your Secret Base, or at their own Secret Base (if they're not one of your buddies)
Battle Resort Trainers
If you walk around the Battle Resort, you'll find multiple people that are willing to battle, with their teams based around a certain (Poison, Ground, Bug, Grass, and Fairy)
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