Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
I switched to get priority aqua jet. It almost backfired. If I chose to stay in and let Azumarill die, my Gastrodon would have lived your next attack and used Surf/Ice Beam for the kill.
Those Light screens and Reflects make things really tough for me though. That Espeon was the one I wanted to take out the most because those screens ruin half my team. haha