MTP | Mario & Luigi Superstar Saga DX - Wiggler Boss Fight Skip - @MilsTailsPrower | Uploaded 2 years ago | Updated 3 hours ago
Two glitches are used for this skip.
The first being the Action Command glitch found by Poni64 from the Mario & Luigi Speedrunning Discord.
Video by Zan Sav : youtube.com/watch?v=AAxexyFMpAo

The second being the small wall bypass technique found by Snoion.
youtu.be/AnEa2aVAXJ0

Using the small wall bypass technique , you can hammer Luigi into the ground and then going left before activating the Wiggler cutscene.
Luigi will stay in the Wiggler area without getting pushed.
Now to get both characters on top of the wall , switch to hammer by pressing the R button and hold down + right at the exact same time.
Once you have the fruit , you can save and quit to return at the entrance of this room.