Okay, I'm gonna get coverage on this as I count. xD
There are 56 Pokemon that are not part of an evolutionary chain.
There are 90 Pokemon (89 if you're not including 6th Gen) that are the final evolution after two evolutions.
There are 174 Pokemon that are the final evolution after one evolution.
I did this with a computer, so I may be wrong. Especially because it's not a proper calculator, just Microsoft Excel. xD
This also includes legendary Pokemon, this doesn't includes forms.
Altogether, it makes up 320 Pokemon that don't await evolution.
Hope I helped. :)
Source: This, and another page of Bulbapedia which I can't be bothered linking to, and Microsoft Excel for the adding.