Well, Unown will give an ev in both attacks, which is good for mixed sweepers.
But, if you just want special, you should go to Ilex Forest, which has Psyduck and Golduck in the water.
Route 6 has Golduck and Gloom (only in hg, no Gloom in route 6 for ss).
I'm 99% sure there are Glooms above the Resort area in Platinum.
There are Spearow and Fearow in route 9, 16 and 10 for hg.
You can also find Spearow and Fearow in route 225 for Platinum.
Finding just one really good route to train for this in can be hard, so fly between the two routes that I listed for Johto and Sinnoh, I know it's not really what you want, but you'll get better results.
So basically, route 16/9/10 and route 6 (hg). And, route 225 and route above Resort Area (p).
If only there were Xatus in p/hg/ss..... :(
These evs are good for electric types, and electric types also have advantages against most of the pokemon I listed, so if you want to train an electric type in these evs, these areas should be great for you.