My biggest concern with Tentacool at B is that its competing with Mienfoo for the "utility mon" slot. Personally, i have never used Tentacool, so the point of this post is more a point for discussion than a personal opinion.
'Cool brings to a team a great hazard in the form of toxic spikes, a fighting resist, Liquid Ooze to beat drain punchers, and rapid spin. Mienfoo lacks all of these things, however he makes up for it with an increased offensive presence which allows for you to gain/hold momentum as well as let it win some Unboosted drain punch wars, and significantly more bulk to make up for its lack of a key resistance. Rapid spin is pretty much the only thing that tenta has that mienfoo cannot do, but so long as Drilbur and staryu exist there will be better (faster, stronger, able to beat common spinblockers) spinners. So my question is; in a metagame where balanced teams run rampant, is tentacool's support too passive? In otherwords in the turns you have tentacool out are you providing your opponent with too much time to accomplish his goals while you're setting spikes, spinning hazards, etc?
Like i said, i have *never* used tentacool so I really don't have an opinion here, but would really like to know what the more experienced players say. My total experience with tentacool scales waaay back to before the second gligar ban and some one spent 3 turns spinning and setting up toxic spikes, to which i just switched in a Croagunk and set up. Its not a really relevant anecdote due to the differences in metagames and quetionable usage of the mon, but i wanted to provide a frame of reference for how little i know about tentacool.
edit: <3 thanks corkscrew