By pretty quick and reasonable, I mean that it should still be as time consuming or "harder" than the current method(account creation). There weren't any problems with too many shiny gifts given out to the players before the update, so I don't see any reason in making it nearly impossible to obtain one after the update. :)
Edit: This will also reduce the amount of new accounts being created, if they made a feature where you would have to spend the same or more amount of time to find a single Charmander.