And when... exactly, will these hindrances even be relevant? Defensive drops from Crunch or Shadow Ball only have a 20% chance of occurring, meaning that, more than likely, Sylveon won't be Baton Passing anything harmful to its teammates. Furthermore, Pokemon with Intimidate have no business switching into Sylveon, and are usually checked by Special attackers anyway; and being at -2 Speed is rarely any worse than being at -1 (ScarfKeldeo will still beat Heatran (has to be at like 40% to lose to offensive lol); Heatran would've undersped Scizor--with the slightest bit of Speed investment--at -1, anyway; Talonflame will still murk Mega Venu; etc).Baton Pass already constricts Sylveon's 4 MSS. Furthermore, Baton Pass can potentially pass nasty things such as a Speed drop from Sticky Web, an Attack drop from Intimidate, among other things. Sylveon is a cleric - not a sweeper unless it is using Specs. And even then - Steel-types will not always enjoy Pixilate Hyper (252+ SpA Choice Specs Pixilate Sylveon Hyper Voice vs. 252 HP / 0 SpD Skarmory: 187-221 (55.9 - 66.1%) -- guaranteed 2HKO after Leftovers recovery).
I'm not getting why crap like HP Fire is getting a pass (what are you hitting harder? Like, Scizor and Ferrothorn? AND it requires pretty stellar prediction to hit? HP Fire blows) on Specs and something as valuable as [empty] Baton Passing gets pushed to OO. I mean, if you don't want to trade a mediocre coverage attack for free momentum, that's understandable, but it's usually more ideal to fish for an opportunity to clear a path for a Choiced powerhitter.
Also, this is a tad bothering:
What counts as a "surprise" Earthquake? Mega Zard-X and Entei like to carry Earthquake and Bulldoze respectively, so I don't see how it's much of a surprise. Mega Zard-Y (seemed like you'd lumped it in with the other Fire-types, but hey, I could be wrong), on the other hand, is an excellent Heatran lure, and isn't likely to carry Earthquake. Dunno how rational you are with someone that isn't QC, but perhaps it would be better to mention specific Pokemon of baiting Heatran into a sly Earthquake or other coverage move, such as the aforementioned Mega Charizard-Y, physically based Latios, or SubPunch (+ Pain Split o3o) Mega Mawile (not the best examples, but you should get the point).A surprise Earthquake can remove Heatran from the game, allowing you to more freely spam Hyper Voice.
Also, given that Specs can't heal at all, could you please consider mentioning Defog / spin support from Sylveon's team? Lastly, though you do mention this in CC, wouldn't you agree that 'Roar / WW beating Protect' is something suited for Usage Tips as well? If I see a Heatran, Hippwodon, or Skarmory in Team Preview, I'd be inclined to play my team, Sylveon especially, a lot more conservatively. Not saying that it shouldn't be in CC, but something such as that just seems important enough to mention on the set itself.