Ah, glad that BP teams are getting attention for a nerf !
I think it's an issue that should've been adressed since at least last gen, but better late than never ! It has always been a controversial issue since it's not easy to find a compromise (some people, myself included, wanted to suspect the move baton pass back in Excadrill/Thundurus Suspect in gen 5, even tho it has some legit uses outside of BP chains). Just like Swagger teams which got nerfed last suspect, it has always been something we all hate facing or losing to (for relevant players, at least).
Basically, if you don't bring (very) specific counters to it, like prankster taunt (commonly taunt thundurus and sableye, even tho the two of them arent that common, especially the later), priority set-up sweepers (which can be played around, even tho flying mons are lethal if the opponent doesnt play zapdos or something), perish song (does that move even exist?) or haze (lol), you've basically lost the match (without taking in account well timed crit, but hue). Another thing that makes BP teams lethal is the move Stored Power, which can bypass the Unaware issue and, more generally, make those teams unstoppable. For instance, you just need seven boosts (which arent hard to get with speed boost, vapo's acid armor etc), taking in account a +6 boost in SpA to ohko 252hp Aegislash with 0 SpA Espeon (just taking a random example, but i think it's pretty relevant on its potential).
It's a very matchup reliant playstyle, but my point is its answers are so specific that you just cant include them on every build. Even if you're playing priority set-up mons, which are commons in xy (bd azu, diggersby, talon, pinsir..), if you lose your "only" occasion of cripple their strategy (which are based for the most part on 50/50 with vaporeon n shit), you can just wipe your salty tears with the -30 that you just got by wasting your time on a pointless match. Even your average novice player can do things with it with little to no effort (i.e not to choke), since it's a very linear playstyle which doesnt require much thinking to make it work.
About the suggested options, at first glance i think the second option is better, but i havn't put enough thoughts on it atm.
That's my two cents about what i think is one of the biggest bane of competitive metagame. I'll elaborate more on that later since i just threw my thoughts in a unorganised way.
Since everything is better with pics, here's one that sum up p.well the feelings when facing BPs
tl;dr : bp are gay, nerf pls