It's
Peanut Butter Jelly Time!
Suggestions:
- Add Swift Swim to Jellicent's viable abilities and move it to Mid-B rank.
- Rank Tentacruel, probably at C, with Magic Bounce.
In order:
With rain support (not terribly difficult to provide in this meta), Specs + Water Spout Jellicent is the closest thing we have to a rain version of Chlorotran. It lacks the sheer power of Heatran, but it still outspeeds and OHKOs a substantial portion of the meta -- Zapdos, Terrakion, Entei, Heatran, Lucario, Thundurus, Gengar, Blaziken, Mandibuzz, Landorus/-I, and a lot of miscellaneous 'mons among them. If it manages to catch something on the switch, a lot of other 'mons fall to it as well. Overall, it's a solid Swift Swim sweeper, packing a slight element of surprise and more than sufficient power and speed. It can sometimes even get a free switch-in on Fighting/Normal-type moves.
However, the Swift Swim set requires support in several ways. First and foremost, Jellicent needs a rain setter. Second, opposing weather (and Water-immunities) need to be removed. Third, as its power is directly proportional to its HP, it is inadvisable to hard-switch it in, and requires a Volt/Switch/Pass or coming in to revenge. Third, hazards should be off the field. And fourth, priority should be removed as much as possible. This does seem significant, but most offensive teams already have a switching move, hazard removal is made easy either via one of the tier's excellent defoggers or Magic Bounce, and teams without priority answers are honestly quite bad anyways. Removing opposing weather/immunity is the only one of these that I think would require some serious dedication.
As Jellicent can effectively perform both support and offensive roles, but with significant flaws, I feel that Mid-B rank is an accurate assessment of its viability. Low-B is also acceptable if the Swift Swim set doesn't bump it up a notch, but Swift Swim is absolutely a good set for it (and more generally, rain is good enough to be worth using in this meta) and should be listed in its viable abilities.
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Tentacruel's niche in AAA is that of a Magic Bouncer that can use the following (but not all at once):
- Rapid Spin, making it a self-contained hazard control package that can't be Taunted.
- Knock Off, to annoy the opposing team and handle spinblockers.
- Acid Spray, to wear down some CM users and other walls.
- Scald, which requires no elaboration.
- Toxic Spikes, to wear down the opposition.
Other users of each of these moves handily outclass Tentacruel, but Tentacruel is effectively unique in its ability to pull off a set with any four of these moves (or Sludge Wave, but I've never felt the need for it). Its unique typing gives it a stable of resistances to good attacking types -- again, any given one (or pair) of them more easily tanked by other Pokemon, but Tentacruel's niche is in resisting all of these, with its weaknesses not terribly difficult to account for. Between these qualities, it is a good Pokemon to cover a variety of utility roles in only one team slot, should your team need that.
Tentacruel's most serious flaw, and the biggest reason to use lots of other things, is that it has no reliable recovery. It will get worn down fairly quickly if it tries to stay in against something with solid attacking stats, and even fully invested, it despises taking the powerful neutral/boosted hits that are abundant in this meta -- its defensive stats are not stellar.
I thus assert that Tentacruel fulfills the definition of a C-rank Pokemon -- it has notable niches, but also serious flaws. It does not require significant support (it
is support), but is instead limited in the number of teams that it can effectively support. It faces a lot of competition from common, highly-ranked support Pokemon for a team slot.
Footage of Swift Swim Jellicent in the wild