I'd suggest:
1. Create a cloned backup of the 2012 on an external drive, using either CarbonCopyCloner or SuperDuper.
2. Connect the cloned backup to the new MBP.
3. Now you have a choice:
3a. Use Migration Assistant to "selectively migrate" stuff you choose to move over. Be aware that you cannot pick and choose among apps -- it's either "all" or "none".
3b. Do a "manual migration" by hand. Be aware that with some applications, if you copy only the app itself, you may be "leaving other stuff" behind that is necessary for the app to function. Depends on just which apps you're trying to migrate.
Also be aware that you cannot copy the "main subfolders" in your home folder directly to the new Mac. By "main subfolders" I mean the folders named "Pictures", "Music", "Movies", "Library", etc.
HOWEVER -- you CAN copy files/folders that are INSIDE these folders. That is to say, you can copy individual pics, songs, etc.
Also be aware that if you do manual migration, you could run into permissions issues UNLESS you do this:
1. Click ONE time on drive icon to select it
2. Type command-i (eye) to bring up the get info box
3. At the bottom click the lock icon and enter your password
4. In the sharing and permissions area, put a check into the box "Ignore ownership on this volume".
5. Now you can freely copy files from the old drive to the new MBP without permissions conflicts.