Yes, the initial list has some issues, but I wouldn't say it's not competitive. Using my list, which I've tried to keep super consistent with the Octillery engine, I tested 6 matches and went 5-1. Granted, it's not a huge sample size, but it holds true to my testing in the past with the deck.
Wins
Mega Sceptile/Vileplume (What should've been an auto-loss was a domination simply because I could OHKO EXs)
Xerneas BREAK/Giratina (Really close actually, but I was able to Lysandre a Shaymin early to get ahead)
Primal Groudon/Carbink BREAK (Garchomp is just faster)
Volcanion (full disclosure, it was a pretty janky build, but I was set up to KO every Volcanion on the board w/ Lysandre in hand)
Darkrai/Hypno (Hypno was annoying, but hitting Darkrai for weakness is too easy)
Loss
Rainbow Road (It was CLOSE, mainly because hitting 120 against Xerneas BKT is infinitely easier than hitting 130 against the Xerneas with Geomancy, but Galvantula decimated my 60 HP babies on the bench)
Conclusion: After significant testing, the Octillery build with no Talonflame is vastly superior.