The RX 480 has a "Ellesmere XT" GPU, which will work with any other RX 480s (Ellesmere XT), RX 580s (Ellesmere XTX), RX 470s (Ellesmere Pro), RX 470Ds (Ellesmere) and RX 570s (Ellesmere XL) graphics cards.
But remember that the crossfire performance will always be limited by the slowest card, so if you paired it with a RX 470D you'd only get the performance of 2x RX 470D and lose the performance of the RX 480.
The RX 460 has a "Baffin" GPU which isn't crossfire-compatible.