There are no Weight Watchers apps that are not made by WW. They have trademarks on anything that uses their point system. The only thing close that can help would be My Fitness Pal. Although they count calories, its a similar system to WW, I just don't know how well it works though.
The Ultimate Food Value Diary Plus is the greatest app and works just like WW mobile app. It is $3.99 for the app and no monthly fees after that. It is on android and iPhone. I also have the galaxy 3 and love it!!