You can restore any backup, but it wont change the type of the amiibo and the game will consider it's data to be corrupted if it happens to be an incompatible type (it'll make you reset the data), but i believe you can backup and restore within the same game type (eg: from one SSB amiibo to another SSB).
As long as you take a backup of the amiibo before you do anything you can restore that backup to revert it to the way it was.
If I were you i'd do:
1) Backup the amiibo with some game data (character customisations etc)
2) Goto the game and change the character data to something different.
3) Restore the amiibo from the backup of step 1.
4) Verify the amiibo has the original data when you go into the game.