Level 100 Statistics (see level 5, 50, 100)
Tangela is a good defensive Pokemon in NU, with Eviolite to bolster its already good defenses and Regenerator to make up for its lack of Leftovers recovery. A decorated support movepool including Sleep Powder, Leech Seed, Knock Off, and Synthesis allow it to do more than just sit around and tank hits. Tangela also has good Special Attack, which both keeps it from becoming setup fodder and allows it to run a more offensive set. However, Tangela's typing tends to hold it back a bit; weaknesses to common Ice-, Bug-, and Flying-type attacks is a huge downfall and force it to rely on its bulk alone to take on a good number of attackers. Meanwhile, its good movepool still misses out on some great support moves, such as Will-O-Wisp, Heal Bell, Taunt, and Baton Pass, making Misdreavus and Musharna better alternatives for many teams.
With a base 115 Defense boosted even further by Eviolite, Tangela is the epitome of physical walling, able to survive even a Choice Band Rapidash's super effective Flare Blitz. Regenerator greatly helps in this endeavor, making it difficult to wear down Tangela as it can recover its health simply by switching out. Giga Drain makes for a solid STAB move backed by a base 100 Special Attack while also giving extra recovery to Tangela. Leech Seed is one of the most important moves in Tangela's repertoire as it not only helps by giving extra recovery for walling and sapping away at the opponent's health, but also by deterring switch-ins such as Musharna and Gurdurr from setting up, as well as creating setup opportunities for your teammates. It is Tangela's most distinguishing feature from Vileplume, and the utility it provides is so valuable that you might just be better off using Vileplume without it. Though Synthesis may seem like a strange choice considering how much recovery Tangela already has, it helps greatly in stalling for Leech Seed and recoil damage and when a lot of hazards are stacked on your side of the field. Combined with a Leech Seed on the switch, Tangela can stay in on even Choice Band variants of Rapidash and Braviary and take the hit, use Synthesis, then switch out, regaining almost all of its health thanks to 50% + 33% recovery, while also draining 25% of their HP and making them take damage from recoil. Sleep Powder is still an option over Synthesis as, despite being inferior to Spore, it is still able to cripple a Pokemon for usually the whole match. Hidden Power Ice gives good coverage alongside Giga Drain, hitting Grass-, Flying-, and Dragon-types super effectively and greatly reducing the number of Pokemon that can set up on Tangela. It is especially important for preventing Sap Sippers such as Sawsbuck from having their way with Tangela, as well as stopping Fraxure from setting up. Being able to hit predicted switch-ins is pretty nice as well.
Team Options & Additional Comments >>>
Though Tangela has a reputation of being a harmless wall, it can also go on the offensive with a more than decent base 100 Special Attack. Combined with a 140 Base Power attack and status moves, opposing teams might be hard pressed to find a Pokemon that will enjoy switching into Tangela. Regenerator synergizes with Leaf Storm perfectly, as Leaf Storm's detrimental secondary effect will force Tangela to switch out often, and is perhaps the reason why this set is so effective. However, investment into offense doesn't mean Tangela's walling ability is gone. In fact, Tangela is still significantly physically bulkier than physically defensive Vileplume. Hidden Power Ice makes a return on this set to provide coverage on Grass- and Flying-types. Like most Grass-types, Tangela has a paltry movepool, so Stun Spore is the best move in the last slot. Stun Spore can offset Tangela's low Speed and stops some setup sweepers that would otherwise have their way with this set. Synthesis is another option to recover while staying in, but the nature of Leaf Storm makes this an unappealing choice.
Team Options & Additional Comments >>>
A specially defensive spread can do well against Rain Dance teams while retaining most of Tangela's physical bulk, but Roselia is generally the better choice if you want to go down this path. SubSeed is a time-honored strategy of Grass-types, and Regenerator will help in making Substitutes, but Tangela's low Speed means it can be difficult to do much with such a set. Things such as Sludge Bomb, Sunny Day, and Growth are the remainder of Tangela's miserable movepool, but these are all just outclassed by better options.
Checks and Counters
Taking into account Tangela's lopsided defenses and the Grass-type's myriad of weaknesses, it isn't difficult to find a Pokemon that can force Tangela out. Powerful physical attackers such as Rapidash, Swellow, and Braviary all resist Tangela's STAB moves and can deal massive amounts of damage to it. Zangoose can also break through Tangela after Stealth Rock. Virtually any special attacker can break through Tangela, as even resisted STAB moves will oftentimes 2HKO it. The threat of sleep and paralysis is still strong, however, so ways to avoid them are necessary to fully counter Tangela. Magmar is the most prominent, as Vital Spirit and its Fire-typing make it difficult for Tangela to do anything against it, but Magmar's offensive threat level just isn't up to par with Magmortar's. Substitute users such as SubCM Gardevoir, Klang, and SubBU Braviary can all set up on Tangela with ease. Sap Sippers such as Miltank and Sawsbuck can switch into most of Tangela's moves and take advantage of the Attack boost, but against a healthy Tangela, Sawsbuck will only fall to repeated Hidden Power Ices. Sap Sipper Zebstrika is a bit unorthodox, but it can do the same and also threaten with Overheat. Vileplume poses a serious threat with Sludge Bomb and can take Hidden Power Ice without breaking a sweat. LumRest Exeggutor is another Grass-type that is immune to both Leech Seed and Sleep Powder, and can Rest off the damage from Hidden Power Ice while preying on Tangela's low Special Defense with a strong STAB Psychic. Finally, hitting Tangela with a Toxic, Knock Off, or Trick will greatly diminish it's walling ability by either crippling its defenses or constantly draining its health, a fact that will only be amplified by its lack of Leftovers.