Yes — this can work, but not because the two brands directly talk to each other.

Cactus and PocketWizard use different radio systems, so they won’t communicate over the air. However, a stacked setup can still work if each system is doing its own job independently.

A reported working arrangement is:

• PocketWizard connected under the Cactus receiver
• flash mounted on top of the Cactus receiver
• Sekonic meter using its PocketWizard transmitter function for test firing
• camera using the Cactus transmitter for normal shooting

In that setup, the PocketWizard triggers the flash for metering, and the Cactus system triggers it when the camera takes the shot. So the key point is: the systems are separate, but they can coexist physically in one trigger chain.

Just make sure the specific trigger units support the required pass-through/connection method and that the flash still receives a proper sync signal.