There are 3 ways of getting this achievement:
(1.)One of which is by scanning the the 'Spectral Locomotive' Pinata Vision Card. Link is HERE:
(2.)Second would be to beat all of Kenya's Challenges. Said part of the world's challenges are as follows:
BLUE CHOCSTRICH
PINK ZUMBUG
GREEN CHIPPOPOTAMUS
YELLOW LIMEOCEROS
BLUE ROARIO
Variants can be dicovered by checking each pinata's information at:
http://pinataisland.info/Once you have completed the challenges the item is available for sale in Cosolot's Store, found under 'TOYS'.
(3.)A third way may be to go into someone's garden who already has a Spectral Locomotive in it and it should just pop up. But to be safe use methods 1 and 2.