You need a Beast type or Bulk type alien to be able to reach the platform.
Go to Vulpin 3-Swine Ridge.
If you're on the portal, you'll see a platform above you and two vulpigs lv3. Run then jump attack both of the vulpigs until they stick together. Repeat until they die. You can farm here and you won't get attacked by the monsters. Just don't wander far left because vulmen might attack you.
