Pokemon VGC has had many different formats in the past few years that come in a form of "series" for players to participate in. In the newest format, Series 8, there is a different set of rules for trainers to follow. The main rule is that every team can only use one restricted Pokemon, which are legendries.
With this, there are many legendary and non-legendary Pokemon that are going to be very popular in the format due to their many uses. While there can be many different combinations of good Pokemon, these ones are going to be frequently used.
10 Groudon
Back in 2019, when Pokemon VGC entered the Ultra Series, trainers were allowed to bring two legendary Pokemon with them. One of the most popular picks was Groudon. Not only is this Pokemon cool looking, but it has a very powerful move set and ability. As for its ability, Drought makes the sunlight harsh, causing Fire-type moves to do more damage while making Water-type moves less powerful. This is helpful for powerful Water-types Groudon will go against such as Kyogre or Rapid Strike Urshifu.
The ability also helps potential partners for Groudon such as Venusaur as its ability Chlorophyll increases its Speed in the sun. Groudon also has access to Precipice Blades, which is a very powerful ground move that tears down opposing Pokemon.
9 Kyogre
Just like Groudon, Kyogre also has a weather ability. Drizzle makes it rain, which increases Water-type move power and decreases Fire-type moves. It was also very popular in the 2019 Ultra Series to combat Groudon.
It also has access to a move called Water Spout where its power is based on the HP of the Pokemon, but it does a LOT of damage when an opponent is at full health. Kyogre is also a good partner for Ludicolo as Drizzle makes it faster as well. It does great damage and counters Groudon.
8 Glastrier
One of the most popular new Pokemon to enter VGC is the Ice-type Glastrier. This Pokemon has a lot of bulk to take a lot of hits from opponents. It also has a very powerful ability called Chilling Neigh that increases its attack when it makes a Pokemon faint.
With the item Weakness Policy, Glastrier increases its stats very easily due to its bulk and attack. Plus paired up with a Trick Room, it makes the Pokemon almost unstoppable as a sweeper.
7 Regieleki
Another popular new Pokemon to debut in VGC is Regieleki. This Pokemon serves as very good support as it has access to moves such as Reflect, Light Screen, and Electroweb.
Regieleki is also very fast so it is able to get off its support moves quickly so that the carry Pokemon can sweep the opposing team. It is also able to do a lot of damage in the Electric Terrain that can be activated by Pokemon such as Tapu Koko or Pincurchin.
6 Yveltal
In Series 7, Galarian Moltres was a popular pick for many teams. It has very powerful Dark-type moves if it is able to set up with a Nasty Plot, and it becomes almost unstoppable when Dynamaxed. But with restricted Pokemon now legal in the meta, Yveltal is just a better Galarian Moltres.
Yveltal has better stats and is bulkier. It was also another legendary that was popular in the Ultra Series, plus it would be a good counter for the Ghost-type Pokemon Spectrier.
5 Xerneas
Yet another legendary Pokemon that was popular in the Ultra Series was Xerneas. Once this Fairy-type Pokemon is able to set up using Geomancy and raises its Attack, Special Attack, and Speed, it is almost unstoppable.
Xerneas becomes a huge threat to any Pokemon team once it does set up. Xerneas will be a monster paired with a support Pokemon that has Follow Me that forces damage away from it.
4 Tapu Fini
Tapu Fini is one of the best bulky supports in VGC. Its typing and bulkiness make it able to take a lot of damage for a carry Pokemon and be able to do chip damage onto the opposing trainers' fighters.
Tapu Fini also has access to Icy Wind that hits both opposing Pokemon and lowers their speed, which can be crucial in a match when it comes to who moves first.
3 Ditto
This little blob of a Pokemon is going to be very popular in the Series 8 meta for many reasons. Ditto has the ability to transform into any of the opposing team's Pokemon that are on the field, including legendries.
This means Ditto can add another legendary onto the player's team instead of just one. It does not even matter WHICH legendary, but it still means adding a strong Pokemon.
2 Incineroar
One of the best Pokemon to be in VGC from the Alolan region is Incineroar. This Pokemon has many good qualities that benefit a team in battle. The ability Intimidate reduces the enemy team's Attack, which can make a huge difference in tight matches.
Incineroar also has access to Fake Out, which is a priority move that strikes first and makes opponents flinch. Incineroar is also a great damage dealer with Flare Blitz and Darkest Lariat.
1 Amoongus
This mushroom Pokemon is yet another great support for some powerful teammates. It has access to many status moves such as Spore, which makes the target Pokemon paralyzed. It also has access to Rage Powder which makes it so the opposing Pokemon's moves hit the Amoongus instead of its partner.
Amoongus can also have many other supporting moves that help out the damage-focused Pokemon.