It solely depends on your ability to promote your game. If you already know a well-known site that gets a lot of visitors daily, you can pull it off with ads. Sponsors are there to take care of the promotion part for you.
Some sponsors allow ads though. I *think* Kongregate allows Mochi Ads, but you'll have to read their FAQ to confirm this, as well as being hosted on another site as long as that site is okay with Kongregate hosting your SWF as well.
Quite a lot of sponsors allow you to upload your stuff on NG, like ArmorGames, MonkeyGames and Kongregate (the last allowing you to upload it anywhere).