Mart worker glitch
Stand on a Tree in Emerald is a glitch where you talk to the PokéMart guy in Oldale wuth a full bag and he leads you into a tree.
Requirements
You must have a full bag. You could NOT have talked to PokéMart guy in Oldale.
Procedure
1. Talk to the PokéMart guy in Oldale.
2. Walk north, one step outside of town. Then talk to him again from the the left side and let the rest happen.
3. Walk right through the Mart and get forced onto a tree!