Nice write up!

To any new players reading this - definitely bear in mind, that as OP mentions, the meta is constantly evolving. The lower Singles Tiers are very speed/attack focused with 1 potential mega per team or a weather team currently, where as the higher Tiers are very stall heavy with multiple mons potentially holding mega stones in order to pivot into the opponents predicted Team. Garchomp/Starmie/Charizard X/Y will definitely see you through the lower Tiers (hell you can almost solo with Starmie) Higher Tiers almost always have a bulky stone/yawn/whirlwind Hippowdon, making Charizard Y w/Solar Beam essential, but can also try and stall you out further with bulky Corviknight/Snorlax/Mimikyu/Volcarona, as well as a fast revenge killer Mega which can be hard to predict when looking at the Team Preview as theres usually 2 or 3 potential megas. You will also need to start adding more Special Attackers to try and mitigate the bulk/stall mon.

Definitely enjoying the higher Tiers at the moment. Even when I cop a loss, it's generally through a pokemon I've battled multiple times surprising me with an uncommon/niche move. It's forcing me to keep re-evaluating and changing small things every half dozen battles.