The metagame is too physical not Goodra. Goodra is a great special sponge, but outside of Special Mega Lucario, Mega Zard Y, and mixed Aegislash (struggles vs Iron Head) it's almost all physical attackers.
Pinsir, Azumarill, Mega Zard X, Conkeldurr, Mega Medicham, Mega Heracross, Garchomp, Talonflame, Excadrill, Tyranitar, Scizor, Mega Tyranitar etc
You're being too ignorant with your list. You're ignoring that Mixed Aegislash, Mega Lucario, and Mega Charizard Y are very popular (usage) and you are ignoring its ability Gooey which punishes most of the physical attackers on that list like Garchomp, Mega Pinsir, Mega Charizard X, Scizor, and Excadrill (on Iron Head). They are very popular not to mention how Gooey can save you by switching on a contact move like Waterfall and Fire Punch. Dragon-type has a good defensive presence as it resists Electric [Thunder Punch], Fire [Flare Blitz, Fire Punch], Water [Waterfall], Grass [Wood Hammer]. It can also sponge a Draco Meteor from Latios with 252 HP and OHKO back which is something that is highly appreciated. In addition, it has excellent Special Bulk. Oh wait, I said that. You were to ignorant with your list. Special Attackers:
Greninja, Aegislash, Deoxys-S, Mega Venusaur, Mega Lucario, Mega Charizard Y, Gengar, Keldeo, Landorus-I (Sheer Force set is more common), Thundurus-I, Thundurus-T, Tornadus-I, Tornadus-T, Manaphy, Genesect, Alakazam, Mega Alakazam, Mega Gardevoir, Mega Manetric, Rotom-W, Heatran.
When you said "it's almost all physical attackers", I laughed (in my mind lol). Yup, there is a lot of special attackers and it can punish contacters too.
Your most possible statement would be "why is it B+ Rank then, not A". Slow without Gooey thing, and needs to rely on Draco MEteor or super-effective damage to actually do some good damage. Other than that, its a sitting duck against something its coverage doesn't work on. also suffers 4MSS since Draco Meteor + Fire Blast are a must and physical bulk isa disappointing (don't get me wrong though, Gooey is good). For these reasons,
Goodra is B+ rank, so IMO, it will stay. B is to good for it.
EDIT:
PHP:
Mega Lucario OHKOs it with a +2 Flash Cannon and Aegislash Shadowball with a spooky plate after rocks is almost an OHKO.
Laurel
How does 2 PKMN ruining it change Sableye's rank to "C at best". You are also not guaranteed Lucario got the Nasty Plot boost.