Went to a locals right after everyone else went to regionals. I actually did insanely good despite losing 1-2. But all my matches had my opponent desperately try to scrap together an answer to my weird card choices.
I played Gholdengo ex with Aegislash as my answer to the unhealthy use of ex and V cards. AEGISLASH WAS THE CARD TO CAUSE PROBLEMS. My opponents used too many ex and V Pokemon and I was only countered by experimental strategies that use regular Pokemon. Last game I was starting to brick and lost because the guy was using Gholdengo ex and Palkia V and was forced to attack using Radiant Greninja. He literally couldn't make a good attack with anything else due to Mysterious Shield.
My strategy does have a hole though. Underused cards/attacks that get around Agislash's ability or status conditions are a big one. Single prize strategies may also prove troublesome. But Gholdengo is supposed to handle most of those.
My use of new cards and more obscure cards took people by the spine. We were rotating early so I utilized some of the new cards with way more enthusiasm than others. Cyphermaniac works wonderfully for Gholdengo as you rig your deck and draw the cards you want. Smart service Indeedee is one rarely ever used, even had a judge call on it because it's first move is worded a little weirdly and has rarely been explained. I know it's a little slow and takes up the active spot, but you got to admit that grabbing any card and being able to use the move on the first turn is great.
The biggest problem is mirror matches as Scizor is commonly used in Gholdengo decks. Scizor does insane damage if I get set up.
To be clear: Full Metal Lab is a good card to run for this deck, but Gholdengo ex is too commonly used to safely play. Rigid Band is not bad; you'll probably be playing this with Arvens.
This may be close to meta, but I like to mix some odd strategy to make my opponents panic.