It was a bunch of tiny things, mostly related to Garchomp. Garchomp was your ace-in-the-hole, not because of its raw power but because it could duel favorably in all possible matchups. Its versatility was vital to its pressure -- therefore, your first mistake was equipping it with Ring Target instead of Expert Belt, since Ring Target only slightly boosts your damage vs. Crobat compared to Expert Belt while gimping all of Garchomp's other matchups. Versus Crobat, Ring Target Earthquake does 22.5 dmg, but EBelt Stone Edge does 22 dmg and Rock Slide does 19 dmg. The damage is very close. However, versus Zoroark, Ring Target Brick Break only does 16.5 dmg, but EBelt Brick Break does 20.5. It's the difference between a 4hKO and a 5hKO. When you consider that I want to switch Zoroark in against Garchomp (my alternative opponents are Revenankh and Infernape), the equipment seems like a clear decision to make -- you pick the item that accentuates your mon's strengths and also punishes me for doing what I want to do most.
Your second mistake was not catching my Sleep damage threshold blunder, obviously. If you caught that mistake and capitalized with an EBelt Brick Break, or even by Sand Tombing into Infernape, I would've been in a tough spot.
The last meaningful mistake I could find was your raw switch after Round 5 into Infernape. You could've still stayed in and spammed Rock Slide hoping for flinches, at least. Raw switching into Infernape sacrificed the Bulldoze speed reduction, costed you 6hp from hazards, and gave me complete choice over which matchup to pursue. Matchup control is typically one of the most vital aspects of BBP Singles, and I don't think the second order was worth giving it up in this case. As evidence that this was a mistake, from Round 5 onwards you never substantially regained control of the match. I got all the exact matchups I wanted from Round 6 onwards.
What was a good equip was giving Ring Target to Revenankh, which I had not considered as a possibility and was completely unprepared for. And when you prevented me from attaching Sticky Barb with your combo, I became legitimately worried. With so few Pokmeon remaining, Ring Target's specificity was no longer exploitable. I was very glad to have second order on the final round, believe me.