There's a Pikachu nest at the back of my University. Caught 3 within 5 minutes. I fortunately have enough candy to evolve Pikachu, so I don't need the extra Pikachu - can't be bothered spending 45 getting there just for that. I would have liked to known about it before I buddied my Pikachu for the candy though.
I still need candy for most of the Jotho evolutions. I have Zubat and Eevee prepared so far (easy jobs, thankfully Eevee spawn around my house). I'm hoping that they'll release nicknames that can auto-evolve Eevees to Espeon and Umbreon much like Sparky - maybe Sun and Moon to honour the new games. I need one more candy to get Oddish --> Gloom --> Bellosom, but I still need to get Vilepume. I'll probably wait till Jotho before evolving, as I have a feeling that Gloom's evolution will be random once 2nd gen is released, much like Eevee's evolutions. Similar case with Poliwag and Slowpoke; I already have a Poliwhirl (alas one with crap IVs) but no Poliwrath and Slowbro, and have close to enough candy for Poliwrath and Slowbro, but I rather wait till Politoed/Slowking comes out. I only have 31 Horsea candy, but thankfully I have a good IV Seadra.
Onix I only have 22 candy. I've only encountered and caught two Chansey (coincidentally one of them was yesterday). Porygon I only have the one I caught by chance and have never encountered another one. I have never encountered Scyther despite encountering 66 Pinsir.
Coincidentally I only started obtaining >80% Ekans this month. Including a 100% Ekans 4 days ago. Too bad Arbok sucks; otherwise I'd be powering it up as much as possible. Same goes for my other perfect Pokemon: Gengar, Venomoth, Pinsir, Tangela. Though at least when 4th Gen comes around, perfect Tangela will be very valuable.