Why Is Rillaboom in Tier B Despite Its High Usage?

Figures below refer to the October 11, 2026 report, covering September 27–October 11. The linked live reports update over time.

Hello everyone! We're the Showdown Tier team.

This time, we're looking at Rillaboom in VGC 2026 Regulation M-C (Pokémon Champions). In our October 11 report, its usage rate was 37.32%—a substantial presence across the teams in our sample. Yet its displayed tier was B.

How can such a widely used Pokémon be in Tier B? Rillaboom gives us a useful example of how to read the numbers behind the label.

Start with the numbers

In that report, Rillaboom had a 37.32% usage rate and a 50.88% team win rate. Its detail page recorded 245,526 team appearances: 124,914 wins and 120,612 losses. Dividing those wins by the total appearances gives the displayed 50.88%.

These figures come from a sample of publicly spectatable Pokémon Showdown battles over a rolling 14-day window. They do not represent every Showdown battle or results from official in-game tournaments.

What usage and team win rate count

Our usage rate is calculated as recorded team appearances divided by twice the number of analyzed battles, multiplied by 100. Each battle has two teams, so the denominator is twice the battle count.

The detail page reports 328,929 battles, giving 657,858 team slots. Rillaboom appeared in 245,526 of those slots, producing the 37.32% usage rate.

An appearance means that Rillaboom was on the registered team. It does not require the player to select it for battle or send it onto the field. Selection rate is a separate metric. Reading 37.32% as “Rillaboom took the field in 37% of battles” would therefore be incorrect.

Team win rate uses the same unit: wins by teams containing Rillaboom divided by their combined wins and losses. It reflects the outcome of the whole team, including its other members, the opponent, and the players' decisions. It does not isolate Rillaboom's contribution to a win.

A mirror battle, with Rillaboom on both teams, adds two appearances: one win and one loss. The mirror portion therefore has a win rate of exactly 50% and can pull the combined figure toward 50%. The overall 50.88% figure alone does not tell us how much of that effect comes from mirrors.

Where Tier B comes from

Showdown Tier assigns labels using a published matrix that combines usage bands with win-rate bands. It is a consistent way to organize popularity and team outcomes into an overview of the sampled metagame.

Rillaboom's 37.32% usage places it in the “30% to less than 40%” row. Its 50.88% win rate places it in the “50% to less than 51%” column. The cell where those bands meet is B.

At the same usage band, a win rate of 51.00% would produce Tier A. That is a difference of approximately 0.12 percentage points from the displayed figure. Crossing the threshold changes the label; it does not mean the Pokémon suddenly becomes substantially stronger in practice.

Reading the move statistics

The detail page also records moves actually used in battles:

Fake Out: 75,003 recorded team uses, including 37,446 wins; team win rate 49.9%.
Wood Hammer: 48,867 recorded team uses, including 26,159 wins; team win rate 53.5%.

For each move, a team side counts once per battle when Rillaboom is recorded using it, even if it uses the move repeatedly. Both sides of a mirror count separately.

These are conditional team win rates for battles in which the move was recorded as used. They are not moveset adoption rates or the probability that a move succeeds. A move that was available but never used contributes no recorded use, and an unselected Rillaboom contributes none either. Missing or misattributed log records can also limit comparisons.

Opponents, teammates, battle situations, player choices, and ratings differ across these samples. The gap between 53.5% and 49.9% does not show that replacing Fake Out with Wood Hammer would improve a team's results, or that either move is weak.

Instead of automatically choosing the move with the higher displayed win rate, use the data to ask: in which situations does my team need this move?

Putting the data to work

The high usage rate shows that Rillaboom teams were common in this sample. That makes them a reasonable priority for matchup practice.

Start with one Rillaboom team that you encounter frequently. Review replays and note the team members and selections you can observe, along with the situations in which Rillaboom uses its moves. If you use Rillaboom yourself, record when Fake Out or Wood Hammer was needed—and when you left those moves unused. Comparing battles under similar conditions, including rating ranges, makes the patterns easier to interpret.

A tier label alone is not a good reason to remove a team member. Review your losses, form a hypothesis about what your team was missing, and then test a change.

Here, Tier B summarizes where 37.32% usage and a 50.88% team win rate fall in our matrix. On the next update, look beyond whether the letter has changed: check the numbers, consider the situations behind them, and use those observations to guide your practice.