Was anyone expecting Ogerpon to be so cute without its Mask? I wasn't. Ogerpon is fascinating, have a good stat distribution that enables a multitude of roles, and a movepool to match, with its Masks + Grass STAB, healing in Horn Leech, potential priority in Grassy Glide, Low Kick, Play Rough and Stomping Tantrum for coverage, Knock Off for Item disruption, U-Turn for pivoting, Swords Dance for boosting, Spikes for Hazard support, Follow Me for redirection support, and even the insanely rare Spikey Shield for an even better Protect. While Ogerpon is a jack of all trades thanks to its stats and movepool, whether it becomes a master of none or master of all remains to be seen.
Teal Wisp
Ogerpon
-Ivy Cudgel
-Knock Off
-Follow Me
-Spikey Shield
Ability: Defiant
Item Attached: Leftovers/Rocky Helmet
EVs and Nature:
252 HP / 4 Atk / 252 Spe
Jolly Nature
Base Ogerpon has two significant advantages over its other forms being the only one that can use items aside from the designated masks and the only one with the fantastic Defiant ability, enabling Ogerpon to punish use of Intimidate, Icy Wind, Snarl, etc. to actually boost its attack to frighteningly high levels. Ivy Cudgel is the mainstay STAB on every Ogerpon set. It is incredibly hard to turn down a drawbackless Base 100 STAB move. Knock Off provides Ogerpon coverage and invaluable utility removing opposing items like Heatran's and Iron Hand's Assault Vest, Chi-Yu's and Flutter Mane's Choice Specs, etc. Ogerpon getting the insanely rare Follow Me is quite the boon. While not as bulky as other redirectors like Amoongus, Ogerpon is still bulky enough to take a hit or two, invaluable for protecting Chi-Yu, Landorus-T, and Arcanine-H from Urshifu-Rapid. Spikey Shield rounds out the set, which further punishes any contact attackers, enabling Ogerpon to play offense while on defense.
EVs are to get the most out of Follow Me and Defiant, balancing out Speed and bulk, though one can conceivably go for Max Attack and more coverage. Leftovers helps supplement Ogerpon's bulk while Rocky Helmet makes Urshifu-Rapid regret clicking Surging Strikes.
Burning Leaves
Ogerpon (Hearthflame)
-Ivy Cudgel
-Horn Leech
-Spikey Shield
-Swords Dance
Ability: Mold Breaker
Item Attached: Hearthflame Mask
EVs and Nature:
4 HP / 252 Atk / 252 Spe
Jolly Nature
Hearthflame Ogerpon is by far the most offensive variant of the 4, having Superb Fire-Grass STAB that is incredibly synergistic, even moreso in Doubles than Singles. Dragons are rare in VGC formats due to the dominance of Flutter Mane and Chien-Pao and Hearthflame Ogerpon actually has a decent match up against the most popular Fire type Heatran thanks to Mold Breaker ignoring Flash Fire, ensuring Heatran is taking neutral, if not super effective damage from Ivy Cudgel. Horn Leech is Grass STAB and gives Hearthflame good staying power. Spikey Shield is super Protect, and a contender for the best move in Doubles. Swords Dance rounds out the set, enabling Hearthflame to counteract Intimidate and apply even more pressure, with Hearthflame's good bulk easing setup.
Other Options
Stomping Tantrum -destroys opposing Fire types like Chi-Yu, and Armarouge that otherwise don't mind Hearthflame's STABs.
Knock Off -good neutral coverage and the accompanying item disruption is a very tantalizing option.
Water Lily
Ogerpon (Wellspring)
-Follow Me
-Horn Leech
-Ivy Cudgel
-Spikey Shield
Ability: Water Absorb
Item Attached: Wellspring Mask
EVs and Nature:
252 HP / 252 Def / 4 SDef
Impish Nature
The most defensive of Ogerpon's forms, Wellspring Ogerpon highly emphasizes its role as redirection support and being the absolute best Water check available. Follow Me becomes all the more powerful when there is a Water type attacker on the field like Urshifu Rapid, Empoleon or Milotic, utterly nullifying their powerful Water attacks and staying healthy to continue to do so. Or if it safe to do so (like after said targets using Protect/Detect), just outright eliminate them with STAB Horn Leech while keeping Wellspring healthy to continue walling duties. Ivy Cudgel is for Water STAB, eliminating targets like Landorus-T, Bloodmoon Ursaluna, Chi-Yu, H-Arcanine and more. Spikey Shield rounds out the set as the best move in doubles.
Stone Oni
Ogerpon (Cornerstone)
-Ivy Cudgel
-Wood Hammer
-Low Kick
-Spikey Shield
Ability: Sturdy
Item Attached: Cornerstone Mask
EVs and Nature:
4 HP / 252 Atk / 252 Spe
Jolly Nature
Despite Rock being pushed as a "defensive" type, it really isn't the case, and that holds true for Cornerstone Ogerpon, who only resists Normal and Electric. However, Ivy Cudgel immediately gains attraction as the best physical Rock Attack due to the fact it has perfect accuracy. Which is enough to carve out a small niche for this form as an offensive attacker, using Ivy Cudgel and Wood Hammer to bludgeon most foes into submission with rather complimentary coverage (Ivy Cudgel hits Bug and Flying types while Wood Hammer wrecks Ground types). Low Kick is added as coverage to hit the Steel types that otherwise resist both STABs. Spikey Shield is on as the best move in doubles, scouting for attacks, stalling out beneficial effects, baiting Teras, etc.
Other Options:
Horn Leech -good for re-enabling Sturdy if you can get enough healing.
Swords Dance -pushes Ogerpon's damage to Ogre all incredible levels.
U-Turn -good for pivoting and punishing opposing Grass types (re: other Ogerpons and Rillaboom)