iCloud Backup
I lost my iphone 5 and the ios was apparently not current. Now I cannot backup from icloud to new iphone 6 because it says ios 8.4 is required. Is there anyway to get my new phone backed up from icloud?
iPhone 6 Plus, iOS 8.4
It sounds like your iPhone 6 Plus is the one that's not updated - it may have been produced a few months ago in the factory. Try setting it up as a new, blank phone (not using the backup), and updating to iOS 8.4.
Once updated to 8.4, try restoring it again from the iCloud backup (Settings>General>Reset>Reset All Content and Settings).
Does that work?