As a ref, you will most likely not use the actual damage formula to calculate damage. Instead, you will use a special reffing calculator. However, it's important to understand the basis of how we get damage values. One of the most important things you should know about calculating damage: physical attacks use the attacker's Attack stat, and the target's Defense stat; special attacks use the attacker's Special Attack stat, and the defender's Special Defense stat.
- In calculating damage and stats, whenever you multiply or divide a number, the result is always rounded down to a whole number. For example, if a Pokemon with a max HP of 314 loses 25% of its max HP due Substitute, it loses 78 HP, because 314 * 0.25 is 78.5, and 78.5 is always rounded down to 78.
- A Pokemon's stat points in URPG are the stats of that Pokemon at level 100 with max IV points, no EV points, and no nature.
- The PP of moves should be kept in mind.
To roll dice on AIM, use one of the following commands, replacing X or Y with the appropriate values:
Some rolls should be privately done on the calculator or random.org.
Every Pokemon can have one or two types. This image is a chart displaying the effectiveness of every Pokemon type against another. Although the reffing calculator automatically calculates effectiveness, it is important to know the type relationships for the purpose of knowing whether a damage seems correct or not, and for the purpose of Expert Belt.
In DPP and newer generations, whether a move is physical or special is a property of the move itself. In RSE and older generations, a move can be determined to be physical or special by its type.
Physical: Bug, Fighting, Flying, Ghost, Ground, Normal, Rock, Steel, Poison
Special: Dark, Dragon, Electric, Fire, Grass, Ice, Psychic, Water
There are five main status conditions that affect a Pokemon when it is active. A Pokemon may not be under multiple main status conditions at once. Some status conditions end on their own. Certain moves, abilities, and items prevent status conditions, remove them, or alter how they work.
- Burned Pokemon lose 12.5% of their max HP at the end of each turn.
- Burned Pokemon physical attacks deal 50% as much damage as normal
- Fire Pokemon cannot be burned.
- Frozen Pokemon are unable to move.
- Frozen Pokemon have a 20% chance to become unfrozen each time they attempt to move.
- Ice Pokemon cannot be frozen by Ice type moves.
- A Pokemon can't be frozen while the sun is bright.
- If a frozen Pokemon uses or is hit by one of the following moves, the frozen Pokemon will thaw: Cross Flame, Flame Wheel, Sacred Fire, Flare Blitz and Scald
- An opposing Pokemon using a fire move on a frozen target will thaw that Pokemon
- Paralyzed Pokemon have a 25% chance to be unable to move.
- Paralyzed Pokemon have their speed reduced to 25% of its value.
- Poisoned Pokemon lose 12.5% of their max HP at the end of each turn.
- Certain moves cause a Pokemon to be badly poisoned, in this case, the Pokemon loses 6.25% of its max HP at the end of the first turn, then 12.5%, 18.75%, 25%, and it continues to increase by 6.25% for each additional turn. This damage maxes at 93.75% The counter resets back to 6.25% when the Pokemon is switched out and in.
- Poison Pokemon and Steel Pokemon cannot be poisoned.
- Sleeping Pokemon are unable to move for 1-3 turns, which is determined by a private die roll. The sleep counter advances at the beginning of each of the Pokemon's turn.
- Rest always causes a 2 turn sleep.
- The counter resets back to 0 when a sleeping Pokemon switches out and in.
There are also other conditions that a Pokemon can have. These conditions are removed when the Pokemon switches out. A Pokemon may have as many of these conditions at once as possible, along with one main status condition.
- An Infatuated/Attracted Pokemon has a 50% chance to be unable to move.
- Confusion lasts for 1-4 turns, which is determined by a private die roll. The confusion counter advances at the beginning of each of the Pokemon's turn.
- When a confused Pokemon attempts to move, there is a 50% chance the Pokemon hits itself, and a 50% chance the Pokemon move normally.
- When a Pokemon hits itself from confusion, the damage is calculated by using the Pokemon's own Attack and Defense stats with a 40 power typeless attack.
A Pokemon's stats can be increased or lowered in intervals called stages by certain moves and abilities. The highest stage is +6 and the lowest is -6. The following chart displays each stage, the multiplier it represents, and the approximate percentage value of the multiplier.
For example, a Charmander with Defense-4 would have its Defense, 185, multiplied by (2/6), resulting in a Defense of 61, rounding down (you round down when calculating stat numbers).
Accuracy and Evasion
Pokemon can also have altered Accuracy and Evasion, making it easier or harder to hit Pokemon. These work like the stage system of stats, but the multipliers are different. The following chart displays each stage, the multiplier it represents, and the approximate percentage value of the multiplier.
For example, a Scrafty with Accuracy+2 (5/3) using Hi Jump Kick, 90% accurate, on a Zoroark with Evasion+4 (3/7) would have the following chance of hitting: (90/100)*(5/3)*(3/7). This evaluates to 64.28…%, which is not an easy number to roll for. However, if you think of the chance of the move hitting as (90/100)*(15/21), it can be easily rolled for. Roll a 100 sided die and a 21 sided die, if they are both
90 or lower and 15 or lower respectively, it's a hit.
If a move is a critical hit, then for the purpose of that move's damage, it will temporarily ignore any drops in stages for the attacker, any gains in stages for the defender, Reflect, and Light Screen, and then deal twice as much damage as usual. Do note that the status condition Burn still reduces damage of physical attacks. For example, a Sandile with Attack-2 critically hitting a Cottonee with Def+3 with a physical move would be calculated as though both Pokemon are at stage 0 in their respective stats, and the damage would be doubled, like it hit twice.
The chance of scoring a critical hit depends on what stage a Pokemon is in for critical hits. In URPG, moves cannot score a critical hit unless the stage is increased by a move, ability, or item. The following chart displays each stage and what chances they give for a critical hit.
1: (0/16) or 0% in URPG, (1/16) or 6.25% in other Pokemon games
2: (1/8) or 12.5%
3: (1/4) or 25%
4: (1/3) or 33.33…%
5: (1/2) or 50%
6: (1/1) or 100%