Go to the buried relic and beat the regis but leave space open in your toolbox and party get the 3 parts and they form into a music boxthen find mew in buried relicanewhere above registeel. if u dont believe mew is there buy final island(you would need it neway if u wanted to recruit him) and past registeel look at recruitment search. if u want the regis buy the anctient relic area of friends and the can join.