I agree with the idea of Conk going down to A-, and will just say that, while he is the perfect example of a poke that is able to conquer its abysmal speed, he sadly is able to be destroyed by too many things as of late (mainly the fact that his usually double tactic is walled by Fairies usually meaning Ice Punch spam while most Psychics usually ran Psyshock any way). So A- Rank is fitting for such a crazy guy.
Gyarados has always been one of those premier Pokémon conquering a x4 weakness with utility and his strength. Him getting demoted makes a little sense, as he has to work with slightly sub par Base power on his STAB (notice I said STAB, not STABs. His Secondary typing rarely gives him something as Bounce was good, but in Megados, he rarely if ever runs a dark type move) usually makes his Base attack stat seem a little lesser. He is still a great attacker, just sometimes seems to be lesser than what he once was.
Then you factor in his Mega Form, which utilizes a few cool things (MB is a god send, allowing him to do so much) but I don't know if that alone is able to keep him A Rank. I want to say stay where he is, but maybe A- is more fitting.
Gyarados has always been one of those premier Pokémon conquering a x4 weakness with utility and his strength. Him getting demoted makes a little sense, as he has to work with slightly sub par Base power on his STAB (notice I said STAB, not STABs. His Secondary typing rarely gives him something as Bounce was good, but in Megados, he rarely if ever runs a dark type move) usually makes his Base attack stat seem a little lesser. He is still a great attacker, just sometimes seems to be lesser than what he once was.
Then you factor in his Mega Form, which utilizes a few cool things (MB is a god send, allowing him to do so much) but I don't know if that alone is able to keep him A Rank. I want to say stay where he is, but maybe A- is more fitting.