NOTE: This spread requires you to customize your speed based on the Gharunder's allies, since you will want Gharunder to use Purgation before specific allies can attack. Choose to remove from HP or ATK for this; for this spread I generally recommend taking away from attack. Use your best judgement to decide who is worth the extra TV investment to outspeed and who is not. Consider using Heavy Armor or, for allies like Yowlar, having 1 SV in speed.
Alternate gear options include Fake beard, Matcha, Energy Drink, Sweatband, Mom's Lunch, War Drum, Refreshing Diabolo, or if you want to go crazy Shuine's Horn. You will have to re-adjust the stamina investment of this spread if you take a stamina-affecting item.
What is Gharunder's role in PVP?
Gharunder is a groovy teammate option that offers support, threat, and unique synergy. Its most standout feature is its trait, Thick Skin, which makes it a Toxic ally option that actively resists wind attacks. Though please note that it struggles to kill said winds within a reasonable timeframe. How much your Gharunder should focus on being a hard-hitting bruiser vs. being purely supportive and unkillable is personal preference, but we'll be covering all the bases today.
What teams appreciate Gharunder?
So far the standard is slower, bulky archetypes that can appreciate purgation and want a Toxic ally that doesn't bring an additional wind weakness. That's a wide-open standard, but expect to see Gharunder on toxic teams (with allies such as Molgu) most often. Of course, being a Purgation spammer with electric synergy can garner favor with allies that dislike toxic or nature threats and love the attack boost (like Garyo).
Specific allies:
Molgu: This is the classic boosted Faraday Cage synergy combo. Molgu has other friends that do this, such as Perfect Jab Mushook, but Gharunder isn't weak to winds which makes it a nice option when trying to avoid stacking wind weaknesses.
Rhoulder: Gharunder naturally outspeeds Rhoulder, and a Rhoulder with +2 attack does scary damage - it can even stagger its own speed with the low priority Stone Ball move. With both Gharunder and Rhoulder being situationally difficult to kill, and with Gharunder immediately being scary toward natures and waters thanks to Wastewater, it may make the opponent have to play carefully with their Rhoulder counters.
Venx: Venx is a slowish attacker that can output massive damage. As a tem that can solidly use Heavy Armor, it makes for a great Purgation target that can be a general added threat to a Gharunder team.
Garyo: A Gharunder next to Auto trait Garyo means the Garyo is hard to kill before Turn 3 unless you are facing a nature...and a Gravel Bag Soil Steam with +2 attack can do some nasty damage. Aside from that fun combo/lead, it offers the same advantages to Garyo as Rhoulder. Gharunder can swap in for Garyo fairly well, as it tends to wall natures and waters while threatening them back.
What is the goal of this specific spread?
First I want to note that while you can take Voltopuncture, it is not a very good move. It can allow for Gharunder to get off one last attack before it dies, it can be used as a stamina-efficient way to remove bait or evades, and it can take off items like Reactive Vial before Gharunder's +2 atk ally hits the enemy for extra nasty damage. However, it will still always feel underwhelming. While it is tempting to take it in order to finish off electric-weak enemies with only red health remaining, it sometimes fails to do even that.
The stamina investment is so Gharunder can use Wastewater 3x and still squeeze in a Purgation here or there. In my experience, sometimes Gharunder lives a little longer than expected, which would have been fantastic at the time if it hadn't run out of stamina. So, we want to give Gharunder stamina so we can avoid situations where Gharunder can only sit there hoping to die. Without a stamina item, you still need a minimum of 23 TVs into stamina to do Purgation + Wastewater + Wastewater, but I often found this deficient. Use your best judgement.
118 Defense gives it useful general bulk when facing offensive physical neutrals. It can also barely survive a Chimurian's Crystal Plume Gatling if you are absolutely desperate, but Gharunder really should not be sitting in front of Crystals in any situation. The second less-expensive but still meaningful physical breakpoint you can probably get is 148 defense for Resistance badge physical Venx, Tardy Rush Rhoulder, or a Purgation-buffed Yowlar. Without this investment, physical attackers will tear through Gharunder in 2 turns (or less if the enemy is doubling you). Since the meta is currently favoring physical attackers, this general defensive investment makes Gharunder less binary.
Now here's where things can get fun. The spread listed is a bread and butter "I hit things good and take hits pretty good" Gharunder. You can slap this Gharunder on most any slower team, adjust the speed so that Purgation moves before your ally attacks, and go on your way. But while this spread is simple, it can get quite complicated. So, here's some extra options.
Max HP with 83 spdef changes Undermine Resistance Badge Momo from a 2HKO into a 3HKO. This basic threshold makes Gharunder an extremely attractive pick into all special attacking threats such as Wiplump, Soil Steam Garyo, and several Digitals. If you don't invest in much def, this spdef gives you enough wiggle room to slot points into offense, allowing Gharunder to still threaten enemies such as Vulffy with wastewater. It is a really nice luxury for Gharunder, since several crystals (except for Chimurian) are special attackers and Gharunder likes to be on teams that have Purgation-able Earth types.
If you want to go for a very bulky "annoying" Gharunder instead of this "bruiser" Gharunder, you will unfortunately have to make some mutually exclusive choices. A tank Gharunder that can take obscene amounts of damage has to choose between being an immediate offensive threat, having extra utility, or having the stamina to maintain that threatening hard-to-kill presence / Wastewater damage. For example, you give up the utility of Bait or Mom's Lunch if you take Sweatband so you can have those Stamina TVS turn into extra TVs for attack.
Tank Gharunder can take 72 total stamina or up it to 81 total stamina and effectively shoot out endless poison ticks, buffs, and still have stamina left for when its Piezoelectric Blow finally comes off hold. Wastewater's damage or stamina are likely to be problematic, however, depending on the goals of the team.
...And if you're one of two people who wants to use Shuine Horn on Gharunder, try 446+ attack TVs so you can 2KO most digitals/water-weaks without the poison tick damage.
But I want to use Brumation!
You will want to have Gharunder hold Matcha and take the minimum stamina (23 SVs). The defense buff is at the end of turn, so it won't help when Turbo teams are now showing up in the meta and can hit you first. But, Brumation can work if you are making an educated decision. Combinations of Shelter, Mom's Lunch, etc may be meaningful on the right team. However, there are reasons this trait is less picked.
Final Words
Gharunder is often called a "fair tem in an unfair meta", but it has a compelling niche. Toxic teams are historically a reliable team archetype and Gharunder is a good toxic buddy, although Toxic teams tend to lean more toward allies such as Nidrasil in this soft-stall high-aggro meta. Despite my consistent mentions of Purgation in this guide, Wastewater is also just a good move, so it can function well independantly of additional team support as long as the team itself benefits well from Gharunder's presence.