^Except aside from Tyranitar, they aren't perfect counters at all.
50% - 58.8% is the amount 252/252 bold Blissey takes from psycho shock.
69.8% - 82.7% is the amount 252/252 Calm Jirachi takes from Sunboosted Hidden Power Fire. (if sunlight is up at all).
I'm not saying that the latios user is perfect and knows exactly what you're going to do at all times, but calling them perfect latios counters would be like calling heatran and magnezone the perfect counters to Choice Band Scizor.
Why the hell would you use psychoshock with specs though (the only way to get the damage roll from the calcs i did)? that'd leave you with DM/Trick/Psychoshock/Filler. If that filler is Hp Fire, TTar laughs at you. If it's surf, everything (including SpDef TTar) laughs at you. Same thing if it's ice beam/ thunderbolt.
(One thing; I got 62.4% - 73.8% from 252 SAtk Specs Latios HP Fire in the sun on 252/224 calm jirachi. Doesn't change anything, just wanted to point that out)
Also, congratulations, SDef Jirachi is sort of countered on the switch 6.2658% of the time. In case you're wondering where I got that number from, it's the percent usage of Ninetails. Otherwise it does 42.1% - 49.5%. Even assuming that you perfectly predicted the Jirachi switch in and got the HP fire off (out of the sun), he can still just T-wave you, then proceed to hax you to death.
Although, I guess your point was that he CAN be defeated, and I guess 6.2658% of the time (assuming all sun teams run latios, which they don't) does count. Still doesn't mean he's anywhere near broken though.
I think the problem we have with your argument is that you're running a 4Hp/252 SAtk/252 Spe Latios @ Choice Specs with Psychoshock/ Trick/ DM/ Surf/ HP Fire and the ability to switch moves. That just doesn't work dude.
I don't think there are any suspects at this point. Especially not Latios. I think everyone would just be happier if there were no more bans at this point.