A- ---> B+/B
While Shell Smash in PU may be a great selling point, generally there's no reason to use Huntail over Carracosta/Barbaracle (mainly Carracosta but I won't get into the whole Carra/Barbaracle argument). Even with Shell Smash, its coverage is pretty bad (just like Crunch and Ice Fang/Beam for coverage other than obligatory Return), and for now, Smash + Sucker Punch is illegal, making one of the only niches it
would have invalid.
Honestly, there's no reason to use Huntail other than SmashPass, which with low speed and bad SpD, common special attackers, as well as phazers (Throh is kinda common and viable), just use the two premier Smashers, Carracosta and Barbaracle, and thus I think Huntail should go down 1/2 ranks.
My points (which are probably invalid and bad)