How do I move WhatsApp to the microSD card?
Moving WhatsApp to your memory card (microSD 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 microSD card at this time. 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 microSD card.
WhatsApp Support Team