First on Mesprit i used the poketch to see in wich route he was, then did the leave/re-enter route Process, then when i found mesprit i threw a masterball at him.
Now on Cresselia it was the wirdest experience ever , so here it goes, i noticed i needed to transfer a woobuffet tht has mean lock, but i still had to wait a day, so i tried to track her down and catch her ( Knewing tht i couldnt ) when she appeared for the first time i decided to throw her a ball , and i only ha dusk balls, so i threw it a dusk ball tht only works in dark places or caves and guess wht? o.0 shaked stoped CATCHED! the first time! it was DAY i used a dusk ball didnt even had to track her down mor ethan once first time i see her BAM! caught! a lv 50 legend with only one dusk ball used o.0