This is an easy way to get Lati@s. It worked for me.

Requirements: Beat the Elite Four.

1)Get a level 40 Pokemon (Perferably Wobeffet)
2)Get an Acro Bike
3)Buy 5 kinds of any Repel
4)go to Slateport city
5)Go to the grass patch next to the entrance of the cycling road
6)use a repel and THEN take out your bike (hold A for 20 seconds)

if this doesn't work then go into the Cycling building, go out and repeat steps 5 and 6 again. Remember this worked for me i dont know about you.