Moves
Sticky Web is the only reason to be running Galvantula, and with it Galvantula can take advantage of faster grounded Pokemon by slowing them down. In a tier full of bulky Water- and Flying-types, Galvantula can pull its weight by using Thunder as a reliable high-powered STAB move to 2HKO most of them. Bug Buzz, the secondary STAB move, combats some common Electric-type switch-ins, such as Hydreigon, Krookodile, and Mega Sceptile, while also threatening bulky Psychic-type Pokemon such as Cresselia. Energy Ball allows Galvantula to hit Ground-types, such as Swampert and Mamoswine, which would otherwise almost completely wall it. Giga Drain is an option to help Galvantula last slightly longer, but it is notably weaker than Energy Ball.
Set Details
Life Orb is almost mandatory to grant Galvantula the kind of power it requires, as otherwise it lacks any kind of meaningful damage output due to a lackluster Special Attack stat. Investing 252 Speed EVs and a Timid nature gets Galvantula up to 346 Speed, on par with Cobalion and Infernape, while 252 Special Attack EVs grant it the most power it can afford. Compound Eyes allows Galvantula to have a 91% accurate Thunder, though Swarm can be used on a Focus Sash set to boost the power of Bug Buzz. Focus Sash is a viable alternative to Life Orb, though Galvantula loses power and usually only functions well as a dedicated lead if using such. However, with a Focus Sash equipped, it can OHKO common anti-lead pokemon such as Aerodactyl, Mega Absol, and Espeon.
Usage Tips
Galvantula appreciates being able to get on the field as unharmed as possible, so bringing it in on a predicted status move or switch can be very beneficial. From there, depending on the team, set up Sticky Web or attack; if the opposing team is offensive, setting up Sticky Web should be a priority, while against defensive teams an attack may have more of an impact than the Speed drop. Galvantula can also wallbreak with Thunder, and once its checks and counters are removed it can clean up a weakened team. When playing against teams with little to no entry hazard control, a good option is to simply lead with Galvantula to set up Sticky Web on turn one, especially if it is holding a Focus Sash.
Team Options
Strong but slower setup sweepers and wallbreakers such as Lucario and Choice Specs Sylveon appreciate Sticky Web support, as they can blow by some checks and counters by virtue of being able to outspeed them. Mamoswine in particular is absolutely terrifying on any Sticky Web team, complementing Galvantula's typing nicely and providing immense firepower. Other options include Crawdaunt, Hoopa, Nidoking, Honchkrow, and Porygon-Z, as they are all slower Pokemon with massive amounts of power, thus benefitting from Sticky Web. A teammate to resist Flying-type attacks would be particularly useful, as Flying-types are the only Pokemon other than Levitate users that are unaffected by Sticky Web in the first place. Mega Aerodactyl is a strong offensive teammate that can provide Pursuit support and attack Flying-types that trouble Galvantula. Metagross can take advantage of Sticky Web while also resisting Flying-type attacks and is able to break through special walls such as Sylveon.
Keeping pressure on Defoggers and spinners is vital, as they remove entry hazards and undo your work. Taunt Mega Houndoom, Mamoswine, and Swords Dance + Stone Edge Cobalion all do the job nicely. Sticky Web in general favors this kind of offense by keeping pressure on and forcing opponents out, though bulky offense works just as well, as the teammates normally found on that build can stomach a hit and punish with a powerful attack in return.