Fallout summons a Nuclear Fallout onto the field for five turns, dealing damage every odd-numbered turn to all Pokémon except Nuclear- and Steel-types. This damage is based on each Pokémon's weakness to the Nuclear type, much like the damage taken from Stealth Rock or a Thunderstorm.
Type effectiveness
Damage (Max. HP)
0.25×
3.125%
0.5×
6.25%
1×
12.5%
2×
25%
4×
50%
Nuclear Fallout also increases the accuracy of Expunge to 100 and reduces all weaknesses of Nuclear-type Pokémon (intended to be by 25%).
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Fallout is the only Nuclear move capable of being learned by more than 1 Pokémon that was not distributed to feral Nuclear Pokémon when their moves were revamped in 1.3.1.