Gary Oak is one of the most popular and recognizable rivals in the Pokémon franchise. As one of Ash's strongest rivals, Gary has long been a competitive force in the anime. However, the battles in the anime are often decided more by willpower and friendship than individual Pokémon strength and sound team composition.
In the Pokémon games, having a competitively viable team takes careful planning, intrinsically powerful Pokémon, and a high level of team synergy. Keeping in mind all of these factors, here is Gary Oak's most competitively viable team, built from Pokémon he has used in the past.
Tyranitar Is a Competitive Monster
Since Tyranitar's first appearance in generation 2, its solid typing, wide moveset, and extremely high base stats have made it a competitive battling monster. Ignoring speed, all of Tyranitar's base stats exceed 90, giving it natural defensive and offensive power. It also has access to a more powerful form, Mega-Tyranitar, which boasts stats of which even legendary Pokémon would be jealous.
Tyranitar's role on the team is somewhat flexible since its well-rounded distribution of stats and moves allows it to be a defensive and offensive Pokémon. Regarding offensive-minded teams, Tyranitar is a great defensive monster that chips opponents down with its sandstorm and stealth rock hazards, while checking nearly all fire, flying, and dark types in the game. Against more defensive teams, Tyranitar can run as a choice banded wall-breaker, dealing huge damage to anything with STAB stone edge and crunch. Since it's strong enough to not be reliant on its mega form, another Pokémon in the team can take that coveted spot.
Blastoise Has Always Been Gary's Ace
Though Blastoise has never been as strong of a competitively transcendent Pokémon as Tyranitar, it has always been able to create its own defensive niche in the meta. As one of the few Pokémon with access to hazard removal moves, a good defensive typing of pure water, and decent defensive stats, Blastoise is the ultimate utility Pokémon for this team.
With the move, rapid spin, Blastoise can clear the opponent's hazards while keeping Tyranitar's stealth rocks on the field. Blastoise is also an important check to opposing water and steel type Pokémon, who will often threaten the hard hitters on this team. With the moves scald and toxic, Blastoise will be able to use detrimental status effects to weaken the opponent's main threats, or simply get the all-important switch advantage with flip turn.
Umbreon Rounds Out the Defensive Core
Umbreon, as another naturally bulky Pokémon, is perfect to round out the team's defense. Though it can be taken out by strong fighting types, there are tons of threatening Pokémon, especially special attackers, that have no way to do meaningful damage to Umbreon.
Umbreon fills the role of a supportive tank, with foul play as its main way of doing damage to opponents. It can also run toxic to pressure bulkier attackers and harass certain defensive Pokémon. Heal bell can be utilized to cleanse its team of status moves. Though it can't do much to pure tank Pokémon that aren't afraid of toxic, it can easily use wish against them, allowing Gary to switch into another Pokémon and heal it for free. This also makes up for Blastoise's lack of self-recovery moves.
Hatterene's Setup Can Steamroll Defensive Teams
With a defensive core set to deal with offensive teams, Gary needs a powerful wall-breaking threat to do well against defensive and stall teams. That's where Hatterene comes in. With its fairy and psychic typing, Hatterene is the perfect counter to the fighting type Pokémon that threaten Umbreon and Tyranitar.
Hatterene's wall-breaking power comes from its high base special attack and access to calm mind, which raises its special attack and special defense by one stage every time it's used. This means that against defensive Pokémon, Hatterene is free to boost its stats up to ridiculous levels before lashing out with massively damaging psychic and fairy-type attacks. With the healing move, draining kiss, Hatterene can easily sustain chip damage from defensive Pokémon like Chansey while it sets up calm minds, and mystical fire gives it an option to hit the steel types that will want to switch into it.
Nidoking's Sheer Force Ability Holds Destructive Power
On the surface, Nidoking's stats may seem subpar compared to the other Pokémon on Gary's team. While true, Nidoking's ability Sheer Force, which multiplies the power of moves with secondary effects by 1.3, more than makes up for its special attack stat of 85. Sheer Force also allows Nidoking to use the life orb item, amplifying the power of moves even more without the detrimental loss of health that normally accompanies the item.
Nidoking's powerful ability and access to an extremely wide moveset make it the ideal secondary special attacker and wall-breaker for this team. With insanely powerful moves like sludge wave, thunderbolt, ice beam, earth power, and flamethrower, Nidoking can provide whatever niche type coverage is needed at the moment, though its low speed means it's best switched into with advantage, which can be set up with Blastoise's flip turn.
Scizor Is a Threatening Late-Game Sweeper
Scizor has been a competitive threat in nearly every Pokémon generation since its inception. Its rare steel and bug typing gives it resistance or immunity to a whopping nine types, with its only weakness being fire-type attacks. Scizor's phenomenal typing mixed with great moves and a monstrous 130 attack stat make it a competent threat on its own, but its mega form is even more dangerous.
Mega-Scizor, with 150 base attack and 140 base defense, is a nightmare for any opposing team. With access to the priority move bullet punch, it can handle quick offensive Pokémon despite its mediocre speed. Given its insane defensive typing, Scizor can use swords dance to set up attack boosts on lots of different Pokémon while using roost to heal up the negligible damage it takes. With a priority, technician-boosted bullet punch, Mega-Scizor can easily clean up the defensive Pokémon that Hatterene and Nidoking damaged and out-speed the opponent's frail offensive Pokémon, giving Scizor huge sweep potential. Mega-Scizor is the main win condition of Gary's team.
There are multiple other Pokémon that Gary could feasibly use in a competitive team, such as a defensive, Intimidate Arcanine, or a hazard-setting Golem. However, this team of six is generally the most well-rounded with powerful Pokémon, strong team synergy, and no glaring type weaknesses.