I have three Apple devices, a Macbook Pro Early 2011, an iPad, and an iPhone 5. The macbook appears to have all of my contacts synched but the iPad is missing a few and the iPhone is missing even more. Each device is connected to the same Apple ID and Contacts is turned on under the iCloud settings for each. I'm not sure what else I can do to get this straightened out.
Make sure that the contacts that are on the MacBook Pro are also in iCloud (www.icloud.com/#contacts) by acknowledging the amount of contacts listed. Including the ones that are missing from your iPad and iPhone. If so, then all you need to do is to turn iCloud Contacts off and back on for the iPad and iPhone.
If they aren't there then these contacts are saved to the MacBook's hard drive. To migrate them, you'll 1st need to make sure that you are on a supported MacOS version. I believe MacOS Lion 10.7.2 or newer is required:
If you have already enabled contact syncing:
Open contacts, then go to users and groups and choose only your On My Mac Contacts to display.
Ensure that nothing is typed in the search field. You might want to backup all of your contacts before you begin. Click to select the first contact and shift-click the last to select them all (or Cmd + A to select all. Then go to File and then Export to vcard and then save it to your desktop (Do another Export and save it to Documents for backup). Delete all the contacts from Address Book (using your delete key). Make sure your iCloud account is your default account (contacts -> preferences > general). Select All iCloud contacts from users and groups. Drag the file you previously dragged to your desktop back onto Address Book.
That should merge those Mac contacts with your iCloud contacts.