I have some forms in drupal 7 using native civicrm, and some using webform integration. The webforms use normal select dropdowns for state and country, but when i create a contribution page in civi, it uses styled select2 dropdowns. I would like to disable this and just have plan selects. Is it possible?
Yes it is possible but you would need to edit the template that is being used. Without knowing where the select box is on your contribution page, I can't say which template you need to edit. I suggest using firebug or chrome dev tools to pick out some of the surrounding html and doing a text search to see which template is being used. Then you can follow the docs for making a custom template.
It is not difficult to do this, but it is not ideal because if the template gets updated, yours will be left behind.
It would be better to add some custom css so that the select2's are made to look like the other select boxes. However I have never found a quick or easy way of adding custom CSS to Civi. If you are already using a custom Drupal theme you could add the CSS to your theme. Otherwise the template method is probably the best way to go.
An alternative way of getting webform selects to match each other would be to make them all select2. It's a nice widget - you might like it :)
This module can do that for you: https://github.com/colemanw/webform_select2
And to avoid needing a 2nd copy of the select2 library (along with a whole bunch of other redundant scripts) check out https://www.drupal.org/project/civi_jquery
In order to work "around" Select2 sometimes behaving inconsistently in automated testing, I've been using this after the page loads to turn those fields back into regular browser selects.
Coleman suggested that it should be possible to use
$('#my_field').val('foo').change() to set values, and this works sometimes, but not reliably enough to test with. The above JS can be executed in a test to make forms behave more predictably.
I wouldn't recommend this approach to address select2 for your site end-users, because they will see a "flash of select2 content" effect :) But since lots of people have answered with ways to deal with this, I figured I'd document this approach.