The bigger questions here are: Is it productive to go out of your way to build a team to beat a team that's not meta? & If you're struggling vs Phoenix, what about the other TM train teams?
I guess it depends on your priorities and where you are in the game. I presume you don't have that many options open to you. swgoh.gg is a must for many things. One of which, is the 'counters' section.
At the end of the day, you'll win what your roster will allow you to win in GAC. I wouldn't fret too much about losses, they're temporary. Just make sure what you do build in the game is relevant and will stay relevant.