chances are if your using reversal blaziken, youre not gonna bust it out until you know what the opponents got. if theres no ss/hail, youre free to do what you want. chances are youre gonna get at least one kill off it. if ss/hail is up you only need to sub 2-3 times to get under 25% hp, then you can coast every turn while youre reversal gets stronger almost every turn.
Firstly, by the time you know your opponent's team, Mixken can already slam through it, WITHOUT almost certainly dying in the process, and can do it while SS and Hail is up
Secondly, Congratulations, you got one kill, my mixken just came in got one, without needing to set up, and switched out to come back later, he then came back later and swept what was left of the guy's team once it was weakened.
Thirdly, with the new boons to SS, there may be 1 out of every 10+ teams lacking it, and then a lot of the rest would have hail. The fact is, SS will once again be the dominant weather of the metagame, just like in gen IV, so the fact is, no sub-reversaler will ever do well unless it's immune to SS, and even then, it's not ideal.
Fourthly, congradulations, you get two, count it, two 150/200 BP reversal just before you die, (~9% or less), and everything prior to that is weaker than my HJK, and it's 99% if I take wide lens, at which point I still have a higher average damage output than you. If I take LO, that just becomes a larger margin.