How do I move WhatsApp to the SD card?
Moving WhatsApp to your memory card (SD card) is not possible at this time.
We are working on improving our application size and memory utilization. There are technical hurdles that do not allow us to move our application to the SD card. In the meantime, we recommend that you help make room for WhatsApp by moving as many other applications and media files as you can, to your SD card.
WhatsApp Support Team