Probably Dragonite, the latest one having 2434 CP and pretty weak IVs. I've encountered and caught two Dragonites in the wild so personally it hasn't been the most uncommon Pokemon for me. I just caught my first Doduo today. I've got quite a list of Pokemon I've only encountered once, of which I would mostly like to meet another Scyther. Another Lapras or another Snorlax would also be nice.