>>52182807i found glimmet in a specific cave in the ground titan's desert area, said cave should be under the river. You'll have to constantly go in and out the cave to reroll the encounters though.
You can also get glimmet at the cave leading to the psychic gym, where they are semi-common (even got an outbreak) but they're much higher level
i didn't use sandwiches or any of the restaurants but they could help, look for encounter power poison or rock
