Purple Munchlax

In the newest update the guy with the supplies is in a big pink building. Near the back of the building there are two doors, the left one being accessible. From the left room, a growlithe is visible in the right room. Unfortunately, I cannot react the right room. Do I have to defeat Taka and ZEL, and then go back to the pink building to find the growlithe before moving right? Or is there another way to get in? I have some images but I don't know how to upload them.