Rillaboom did not climb to second. It arrived there.

· MetaRoll

Rillaboom is second on the ranked ladder three days into Regulation M-C, and it has never stood on a Champions ladder before. The only other time the game added Pokémon to a running roster, in Season M-3, twenty-two arrived and the best of them debuted eighteenth. Grassy Surge is on 100.0% of them, and it is not a personal ability: it adds 30% to its own Grass moves, it hands Grassy Glide the priority that lets a 105-Speed Pokémon strike first, and it halves every Earthquake aimed at the Pokémon standing beside it.

Rillaboom · doubles · the ranked ladder as published at 12:01 UTC on 12 September 2026, and the damage calculator on this site

Two kinds of number on this page. Who it beats and loses to most often, what beats it, what it wins with and who it is brought beside are the ladder’s own figures, read at 12:01 UTC on 12 September 2026. Every damage figure is this site’s calculator, run on the builds the ladder publishes, and is frozen here — the ladder is rebuilt every hour and a report is not.

What arrived

Regulation M-C opened on 9 September 2026 and took the roster from 235 Pokémon to 261, and brought six new Mega stones with it. Rillaboom was one of the twenty-six. Three days later it is second of the 261 Pokémon the ladder ranks, behind Sneasler and ahead of Mega Salamence.

It is pure Grass, and its stat line is 100 HP, 125 Attack, 90 Defence, 60 Special Attack, 70 Special Defence and 85 Speed. Nothing there is remarkable on its own; the ability is. Grassy Surge is on 100.0% of them — Overgrow is the only other ability it can have and now rounds to nothing — and it sets Grassy Terrain the moment it comes out, for both sides of the field, for five turns.

The build barely varies. Adamant on 86.5%, Miracle Seed on 50.0%, and the most common spread is 32 HP / 32 Atk / 2 SpD on 10.8% of them, with the same points moved to Speed on another 7.8%. The moves are Grassy Glide on 97.8%, Fake Out on 96.1%, Wood Hammer on 80.4%, U-turn on 56.2% and High Horsepower on 39.6%. Every figure below is that Pokémon.

The highest debut the ladder has recorded

Champions has added Pokémon to a running ladder exactly twice. The first was Season M-3, which took the roster from 213 to 235, and this site already wrote that up: a debut rank is a ceiling, not a floor. Of those twenty-two, the best debut was Metagross at eighteenth, and two seasons later eighteen of the twenty-two sat lower than they started.

The second is now. Rillaboom came in at second, Mega Salamence at third, Indeedee-F at seventh and Mega Golisopod at eighth. Four of the top eight are three days old. That is not a debut rank behaving like a ceiling; it is a different kind of arrival, and it is the first time the game has shipped one.

It has not moved since. The ladder has published three daily readings of M-C — 10, 11 and 12 September — and Rillaboom is second in all three, with Sneasler, Mega Salamence, Incineroar and Kingambit holding first, third, fourth and fifth on every one of them. Three days is three days, and the limits below say so — but nothing at the top has moved yet.

What it wins with

Share of the wins it records, by its own move

  1. Wood Hammer: 41.7% (on 80.4%)
  2. Grassy Glide: 34.8% (on 97.8%)
  3. High Horsepower: 11% (on 39.6%)
  4. U-turn: 6.8% (on 56.2%)
  5. Fake Out: 2.5% (on 96.1%)
  6. Knock Off: 1.1% (on 7.2%)
  7. Drum Beating: 0.7%
  8. Superpower: 0.5%
  9. Low Kick: 0.3%
  10. Hammer Arm: 0.2%

Two moves take three quarters of its wins, and both are Grass. That is the ability being spent, not the Attack stat.

The ten it beats most often

The ladder publishes the ten Pokémon each one beats most often, most frequent first. Each row is the move that decides that matchup, into a target holding its own item and nature at the bulkiest spread 66 points buy.

Rillaboom · Adamant · 32 HP / 32 Atk / 2 SpD · Miracle Seed

Every target: HP 32 / DEF 32 / SPD 2

Damage dealt, as a share of the target’s HP

The same ten, with the terrain gone

The identical hit with Grassy Terrain not up, and nothing else changed. Three rows do not move at all — U-turn is Bug and High Horsepower is Ground, and the ability pays on neither. On the seven Grass rows it is worth 30%, and that 30% is the difference between a kill and a survivor three times: Mega Gardevoir goes from a guaranteed knockout to a two-hit, and Indeedee-F and Mega Tyranitar stop being rolls at all.

Rillaboom · Adamant · 32 HP / 32 Atk / 2 SpD · Miracle Seed · no Grassy Terrain

Every target: HP 32 / DEF 32 / SPD 2

Damage dealt, as a share of the target’s HP

Grassy Glide, and the Speed it does not need

Adamant at 32 HP / 32 Atk / 2 SpD, Rillaboom is 105 Speed. Four of the ten Pokémon it shares the top with are faster — Mega Salamence at 189, Sneasler at 172, Basculegion at 130 and Pelipper at 117 — and Mega Gardevoir, thirteenth, is 152. On raw Speed it loses all five of those races.

It does not run them. Grassy Glide is 55 base power, 20 PP and 100 accuracy, and under Grassy Terrain its priority becomes +1 — which is to say the ability it brings with it is also the reason its weakest attack moves before everything above. That is the move on 97.8% of them and the second largest share of its wins.

Two things follow. The first is that the 30% in the table above is applied to a move that is already jumping the queue: 71.4 – 84.6% into Basculegion before Basculegion acts. The second is that it only works while the terrain is up — five turns, or eight on the 0.8% holding a Terrain Extender — and when it lapses Grassy Glide is a 55-power Grass move on a 105-Speed body.

The Earthquake half, which is the team’s

Grassy Terrain halves Ground moves against anything standing on it, and that applies to whoever is standing beside Rillaboom as much as to Rillaboom. Garchomp is twelfth and 47.2% of them carry Earthquake; below is that Earthquake with the terrain up.

Dry, the same hits read 21.3 – 25.6% into Rillaboom, 56.5 – 67.6% into Kingambit, 69.3 – 82.2% into Incineroar, 37.9 – 44.5% into Basculegion, 95.7 – 113.9% into Sneasler, 24.2 – 30.2% into Mega Golisopod and 55.3 – 67.5% into Archaludon. Sneasler is the one that matters: it is first on the ladder, an Earthquake kills it outright, and with Rillaboom on the field it is a two-hit instead.

Garchomp · Jolly · 2 HP / 32 Atk / 32 Spe · Life Orb · under Grassy Terrain

Every target: HP 32 / DEF 32 / SPD 2

Damage taken, as a share of its own HP

Six of these seven are on its own published list of the Pokémon it is most often brought beside. The seventh is the one setting the terrain.

The support half

Fake Out is on 96.1% of them, second only to Grassy Glide, and it is not there for damage — it takes 2.4% of its wins. Between that, the terrain, and a Grass attack that removes things in one hit, most of what Rillaboom contributes to a game happens on the turn it arrives.

The terrain is three favours at once. It heals a sixteenth of maximum HP every turn to everything grounded, on both sides of the field. It halves the Ground moves, which is the table above. And it replaces whatever terrain was already there — which matters, because Indeedee-F is seventh and carries Psychic Surge. Psychic Terrain blocks priority moves outright; putting Grassy Terrain over it turns Fake Out and Grassy Glide back on, and takes the boost off Expanding Force in the same motion.

And then there is Basculegion, which finished the last season fourth and is sixth now. A terrain-boosted Wood Hammer does 154.2 – 182.4% to it — one hit, no roll, from a Pokémon whose Grassy Glide already moves first. It is the first name on the list of what Rillaboom beats most often, and that is not a coincidence.

What beats it

Share of the losses it records, by the move that beat it

  1. Hyper Voice: 12.2% (Flying off Mega Salamence, Fairy off Mega Gardevoir)
  2. Heat Wave: 7.6%
  3. Leech Life: 7.6%
  4. Dire Claw: 5.4%
  5. Flare Blitz: 5.2%
  6. Wood Hammer: 5.1% (the mirror)
  7. Hurricane: 3.5%
  8. Expanding Force: 3.5%
  9. Eruption: 2.8%
  10. Sludge Bomb: 2.5%

Three of the ten are Fire, and the only Grass move on the list is the mirror. Grass resists Water, Ground and Electric, and not one move of those three types is here at all.

The ten it loses to most often

The other published list, in the ladder’s order, into the Rillaboom the ladder plays — Miracle Seed, Adamant, 32 HP / 32 Atk / 2 SpD. Six of the ten kill it in one hit.

Rillaboom · Adamant · 32 HP / 32 Atk / 2 SpD · Miracle Seed

Damage taken, as a share of its own HP

The stones Regulation M-C brought in

The same regulation that added Rillaboom added six Mega stones, and three of the six kill it outright. Each row is that Mega’s best hit into the played Rillaboom.

Mega Golisopod is the worst of them: First Impression is Bug, it has +2 priority, and it kills through the terrain with 40% to spare. Mega Salamence kills with Double-Edge and Mega Baxcalibur with Icicle Crash. Mega Garchomp Z does not kill, but it is the clearest example of what the stone changes: the ordinary Garchomp attacks with Earthquake, which the terrain halves, and the Z forme attacks with Flamethrower, which it does not.

The return trip is the problem. Its own Wood Hammer, terrain and Miracle Seed included, does 13.9 – 16.3% to Mega Salamence and 12.1 – 14.8% to Mega Golisopod. Only Mega Absol Z takes real damage back, at 106.4 – 125.6%. Steel, Dragon, Flying and Bug are what M-C added, and Grass hits none of them.

Rillaboom · Adamant · 32 HP / 32 Atk / 2 SpD · Miracle Seed

Damage taken, as a share of its own HP

The Fire, and the berry 7.6% of them bring for it

Three of the ten moves that beat it are Fire, and the two biggest are not close. Torkoal’s Eruption does 179.7 – 212.6% and Armarouge’s Armor Cannon 180.7 – 212.1%. Both are roughly twice what it takes to kill it.

7.2% of them answer with an Occa Berry, which halves the first Fire hit. It is not enough for either: Eruption still reads 89.9 – 106.3% and Armor Cannon 90.3 – 106.3%, both rolls to kill through the berry. What it does buy is everything below those two — Heat Wave falls from 147.8 – 173.9% to 73.9 – 87.0%, Flare Blitz from 81.2 – 95.7% to 40.6 – 47.8%.

The berry costs the Miracle Seed, and the tables above are all Miracle Seed. Without it Wood Hammer into Basculegion drops from 154.2 – 182.4% to 127.8 – 151.5% and Grassy Glide from 71.4 – 84.6% to 59.0 – 71.4%. Both still do the job they were doing; that is most of why the berry is playable at all.

And the Fire that kills it does not stop there. The same Torkoal Eruption, into the Pokémon Rillaboom is most often brought beside, does 265.9 – 316.5% to Mega Golisopod and 154.6 – 183.6% to Kingambit. The Grass and the two Steels share a weakness, and a sun team hits all three of them with one move.

What to make of it

What Rillaboom sells is not damage. Its Wood Hammer kills two of the ten it beats most often, and outside those two the tables above are full of two-hits. What it sells is that the terrain arrives with it, for free, on the turn it comes out, and it does four things at once: 30% on its own Grass, priority on Grassy Glide, half of every Ground move aimed at its side, and a sixteenth of everyone’s health back each turn.

Three of those four are worth more to the team than to Rillaboom. That is what second place is measuring, and it is why the list of Pokémon it is brought beside reads like the top of the ladder: Salamence, Sneasler, Incineroar, Kingambit, Basculegion.

The way to beat it is unchanged from the day it arrived and is written on its own loss list: bring Fire, and do not bring Ground. Whether second place survives a full month is the question three days cannot answer — the last cohort to arrive spent two seasons falling. This one arrived at the top instead of climbing to it, which is the part that has never happened before.

Method and limits