DND_Reborn
The High Aldwin
I think this is really a mountain(20th level) out of a molehill(goblin). This is a rulings over rules game and if someone is importing a single goblin every day for his morning goblin murder, and it's not even remotely close to rising to the level of an easy challenge, I'm not giving experience for it.
If this person is going out seeking goblins to kill, then he's engaging in dangerous behavior, because instead of 1, it might be 100 today. And that's if he can even find one that day. The whole scenario seems silly to me.
I agree it is very silly, but the point is it is possible and at some tables (not ours) you have a 9th-level cleric in every town to raise a fallen friend, and wizards to teleport a party, or whatever. Anyway, it is why our DM often narrates encounter that are very easy and doesn't award XP for them since there really was no threat to the PCs.