Battle Moveset

A Good Moveset for Groudon would have to be this:

Attacks:

Earthquake
Rock Slide Swords Dance
Hidden Power [Bug] / Fire Blast / Overheat / Substitute

Items Attached:

Leftovers
Salac Berry

Preferred Nature:

Adamant OR Jolly

Strategy Using Groudon

Groudon quite simply is one of the most menacing physical sweepers available and in the Uber Metagame quite arguably the best physical sweeper. On top of that it's a fantastic physical wall and can take a special hit fairly decently. Sunny Day helps to cancel out it's Water weakness but it gives it a large weakness to Solarbeam, it also continues to have an Ice weakness which frequently proves to be an Achilles' heel, especially in an environment with fast-paced and hard-hitting special attackers. As mentioned before, Groudon's primary job is a physical sweeper, it's very difficult to find a Pokémon who can truly stand up to it after it's got a Sword Dance in place, but there are a few and that's what the last move is for. The Lati twins are immune to Earthquake (thanks to Levitate) and only take neutral damage from Rock Slide, however up against Hidden Power [Bug] both Latias and Latios will struggle and risk getting 1-hit-KOed after a Sword Dance unless they have a lot of defence. Fire Blast and Overheat can take care of Skarmory who can stand up to your defences and PHaze you although he can't do much else, it gains a bonus from Sunny Day as well which is worthy of note. In both cases both of these moves also do a fair chunk to Grass types who can also counter Groudon adequately, especially with the ones with chlorophyll, Exeggutor is an example of a Pokémon who you're going to want to take out before it gets a move out. Substitute is a solid move on Groudon, it blocks out any potential status attacks, can help Groudon stand against unexpected attacks and can save you having to out-predict switches and can usually stand against physical attackers. If you choose to use Salac Berry you can also Substitute down to activate it.

EV Corner:

There's a lot of ways to go when doing Groudon EVs. If you're running Substitute maxing HP is a given, with Max HP (404) Groudon's Substitutes can block two Seismic Tosses (or Night Shades) and also serve to make them bulkier. The trouble with that is it takes half of your EVs. Max Speed is also popular on Groudon to either tie speed with Kyogre or be guarantied to outrun it, however, since Groudon is one of the slowest Ubers around (and most Ubers run just enough speed to outrun it) some people may wish to run EVs in defences instead. Since Ice Beam is the main counter for Groudon it may be worth considering boosting it's Special Defence in order to survive longer, if Groudon is your only "true" physical wall then you may want to consider a lot of Defence, although Groudon really should never be your only physical wall.

EVs: 4 HP / 252 Atk / 252 Spd
Jolly Nature (+Spd, -SAtk)

A pretty obvious set-up, the aforementioned Max Speed is for outrunning or at least tying speed with Kyogre.

EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature (+Atk, -SAtk)

Max HP for the strongest Substitute, you may want to remove a bit of Attack (and Defence) for Speed to outrun Kyogres that have left their speed at the lowest.

In most cases a more specialised EV set-up is better off, those are just basic templates to work from.

Other Optional Sets

Groudon @ Choice Band
Trait: Drought
EVs: 6 HP / 252 Atk / 252 Spd
Jolly Nature (+Spd, -SAtk) / Adamant Nature (+Atk, -SAtk)
- Earthquake
- Rock Slide
- Hidden Power [Bug]
- Overheat

Choice Band Groudon. Since just about anything with Ice Beam can counter Groudon it saves you the trouble of spending a turn on Sword Dance and gives you a huge attack stat to hit anything that tries to switch in. EQ and Slide are obvious, Overheat and Hidden Power [Bug] counter things that have been mentioned on the main set. You could also try going without Speed (and again, boosting defences), Brave may be a more ideal nature for a low speed set to boost Overheat power, although fire is normally a weak offensive type to use in Ubers anyway.

Groudon @ Leftovers
Trait: Drought
EVs: 252 HP / 4 Def / 252 SAtk
Quiet Nature (+SAtk, -Spd)
- Earthquake
- Fire Blast / Flamethrower
- Solar Beam / Substitute / Hidden Power [Ice]
- Thunder / Thunderbolt

For the most part Special Groudon is inferior to Physical Groudons reducing this set to the point that it's almost a novelty. Both Fire and Grass are relatively weak offensive types to use against Ubers, with a large number of Dragon types (as well as Psychics with high Special Defence) you won't score many super-effective hits. Fire Blast or Flamethrower are pretty much necessities to gain a bonus off of Sunny Day, they are generally its strongest special attack. Solarbeam's only real use is for taking out opposing Groudon's so it can be dropped in favour of Substitute or Hidden Power [Ice] (which can prove to be reasonably useful against the Dragons). Thunder or Thunderbolt can be used for Kyogre, Ho-oh and Lugia, without Rain Thunder has a very low 50% accuracy so you may want to consider Thunderbolt, although Thunder will be a very handy move to catch Kyogre switch-ins, especially with a potential 30% chance of paralysis.

Even without EVs Groudon's physical attack is still better than Groudon's special attack, it needs Earthquake to stop special walls from walking all over it and with the STAB boost it's just generally a good move to have. Creating a good EV set-up for a special Groudon is difficult, ideally you want max Special Attack but choosing a nature to hinder is difficult, Speed is probably the best stat to hinder. As for the rest of the EVs, it's all a matter of preference but you can never go wrong with having more HP.

Other Optional Moves

Counter, Rest, Endure, Roar, Sleep Talk, Thunder Wave, Bulk Up.

With it's high HP and good defence stat Groudon can make excellent use of Counter, the only problem is that very few people try to attack Groudon with physical attacks so the opportunities to use Counter are few and far between. Rest is a good move for something with Groudon's tanking stats, it's especially helpful with Sleep Talk or a team-mate who can Heal Bell or Aromatherapy. Endure can be combined with a Salac Berry but you need to watch out for Rayquaza and Deoxys who can carry Extreme Speed. Roar is a handy move but there's not much out there for it to PHaze that won't be able to put a serious dent in it, and even if it had opponents to PHaze most of the time Groudon is better off hitting them anyway. Sleep Talk was mentioned with Rest but since Exeggutor frequently counters it with Sleep Powder you can catch it by surprise. Thunder Wave is a move that most Groudon counters never want to be on the opposite end of, fast Pokémon don't take kindly to the huge drop in speed and Groudon itself is the only Uber Pokémon with a Thunder Wave immunity. The move fits quite nicely on pretty much any Groudon set. Bulk Up really isn't worth the use, Groudon's defences are fine as they are and as mentioned with Counter, most people don't try to take it down with physical attackers anyway. However if you're playing in 200 mode (Ruby and Sapphire only) there's no access to Sword Dance so Bulk Up is the best choice you have.

Strategy Against Groudon

Very meaty Attack stat, very beefy Defence and HP but a Special Defence that's rather forgettable when compared to the other Ubers. Since it has a Grass, Ice and Water weakness Special Defence is always the stat to target when facing Groudon. Exeggutor can switch in on a Swords Dance and put it to Sleep and then proceed to take advantage of the sunlight with Solarbeam, as can many other Grass types with chlorophyll (although Eggy is the preferred choice). Almost all Ubers are faster than Groudon and pack a relatively strong special attack stat, with Ice Beam added on top of that they have the potential to 1KO and are almost guarantied to get a 2KO.

Both Lati twins are immune to Earthquake, resist Fire Attacks and take neutral damage from Rock Slide but neither want to take a super-effective Hidden Power or Thunder Wave. Skarmory is immune to Earthquake and shrugs off most Rock Slide damage but can't really do anything to Groudon aside from PHaze it, Weezing is a different story since it can Will-o-Wisp but if a Substitute is in place Weezing is out of luck, neither want to take a Fire Attack with the Sun up however. There's a fair share of Pokémon who resist (or are immune to) Earthquake and only take neutral damage from Rock Slide but they need to watch out for what Groudon carries as it's forth move, they also need a fair bit of defence since even weakened attacks can hurt a lot after a Swords Dance and if they lack the ability to threaten Groudon then it can sit there and max out Swords Dances and KO your 'counter' slowly. One-on-One on equal ground Kyogre always scares away Groudon but a Kyogre up against a Groudon with a Swords Dance in place is a different story so Kyogre isn't a particularly reliable counter, it needs a lot of Defence and HP to stand a fair chance.

Contest Moveset

A good Contest Moveset for Groudon would have to be this for the Tough Contest best with Impish, Lax, Relaxed or Bold Nature:

Attacks:

Aerial Ace
Earthquake
Fissure
Hyper Beam

Items Attached:

Yellow Scarf

Strategy Using Groudon

If you do the attacks in this following order you should have very few problems; 1st - Aerial ace, 2nd - Earthquake, 3rd - Fissure, 4th - Aerial ace, 5th - Hyper beam

Locations in Games

Ruby/Sapphire/Emerald Cave of Origin (R), Trade from R/E (S), Terra Cave (E) Colosseum/XD Trade from R/E Fire Red/Leaf Green Trade from R/E

Animé Appearences

Groudon has had a few Animé Appearences. First Team Magma were monitoring it, when later Butler created a Fake Groudon. After that, Team Magma awoke Groudon and caused it to have a mssive fued with Kyogre that almost destroyed the Planet Movie 6: Jirachi - Wish Maker Episode 312: The Spheal of Approval! Episode 359: Unfair Weather Friends! Episode 373: Gaining Groudon Episode 374: The Scuffle of Legends