As for good Places to catch certain Pokemon I recently realised a pretty good way to get some Pokemon: The EV-Train Routes, especially the first two ones.
First is in Kanto, Route 24. You can easily get Pidgy and Coffing from your Boss guide and also Caterpy (thought you probably got one and Butterfly isn't that good), Jiglypuff (is T4 and the hardest to hunt there), Oddish, Kappy and Tentacool. You can try catch a Slowking here but he is harder to get than a Slowpoke elswhere and as a evolution harder to train.
Next is Johto, Route 31: Here you can farm Sentrets. Also Ghastly, Sandshred, Zubat, Whooper and Seel but they are more situational and as Ghastly as a Desteny-Boder does not need best IVs you probably already have one.
The others I just know theoreticly, since I haven't reached them yet, so take my take with a grain of salt.
Hoenn is imo situational: On Route 120 Mareep and the Nidorans are available long before, but if you are farming for IVs it might help. The rest are already available in EV-Zones or are evolved.
In Sinnoh afaik it is somewhat better: Route 208 features Dunspace, Patrat, and Licktung (Rarer) as new Pokemon.
I know these Infos are probably quite obvious to most players, but again, since I didn't think of them as easy farms until recently, I think other newbies may apreciate the hint. I knew I would.