Hey there!
I added the Events category tag to your post to allow others to quickly see what sort of trade you are offering. Be sure to use it in the future to allow people to efficiently browse through the forum list!
As for you trade request, I have Latias in Sun and can obtain Latias from Ultra Sun as well (for level 100 + Bottle Cap). The event is a Wi-Fi event here though, so I'll have to redeem it myself and then trade it to you, just as I'll need you to redeem the event on your end to trade Latios to me. I'm also happy to return a clone of your Pokemon so that you can have both Latios and Latias. I'll be on WiFi in an hour, or around this time tomorrow, if you're happy to trade.