Why are people consistently arguing that because a pokemon can run coverage moves for its checks (and predict their switch-ins), they are all of a sudden broken? Latios is just like any other coverage sweeper in that regard, and it did in fact gain various checks.
SpD Tar, SpD Scizor, Jirachi, Metagross, Tornadus, Thundurus, Starmie, Ferrothorn, Escavalier...the list goes on. You don't need to 100% counter Latios for it to be unbroken. The metagame adapting to its presence is not evidence of it being "broken," either. It is akin to Gliscor running Jolly to check Ice Punch Lucario post Platinum.
SpD Tar is not a new check
SpD Scizor is not a new check
Jirachi is not a new check
Metagross is not a new check
Tornadus and Thunderus are not checks at all, they are OHKO'ed by Draco Meteor, and 2HKOed by any common move Latios carries, except maybe HP Fighting for Tyranitar. They cannot OHKO Latios either.
Starmie is not a check. See Genies, except Surf does not 2HKO Starmie.
Ferrothorn is a check, but dosent stop Latios coing back in later, and taking another 30~40% out of it. Or predicting it and using HP Fire, which it should carry.
Escavalier just forces it out, and even then, only on a DM. Surf will ruin it.
Tl;DR: Latios only gained two, shakey checks [Both are countered by HP Fire, which IMO, all Latios should be running, as it ruins 3 'checks' and hits Metagross and Jirachi hard too, ESPECIALLY in the Sun]
Gen 5 also gave Latios no counters, and removed Blissey as a Counter, due to Psyshock. It also removed Snorlax as a check. So, that's a net gain of +1 Check, and -1 Counter.
And there's other sets besides Specs too. Calm Mind Latios can take advantage of the switches caused by Specs Latios, for example, and can switch moves, while retaining the same power as Specs Latios [You CM on the switch it forces]. Or Life Orb Latios, who could carry Recover.
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Also, people need to stop moaning about the whole of Blaziken being banned. Speed Boost is a part of Blaziken. Banning Speed Boost on Blaziken is akin to banning Draco Meteor on Latios, or banning Dark Void on Darkrai. Speed Boost is a part of Blaziken.
And anyone using the Drizzle + SS ban to justify Blaziken should not be Uber in total: Is Perma-Rain part of Kingdra? No. Double Speed under perma-rain is. The combination was banned, to prevent the destruction of a whole playstyle [Rain Stall], and to prevent at least 3 individual pokemon being banned needlessly. [Kabutops, Kingdra, Ludicolo, and maybe Goyrabass [I hate the spelling of that] and Oymastar, or even Floatzel]
Not to mention SS+Drizzle is an Ability-Ability ban. Not a Pokemon-Ability ban. So there is no precident.