Head Smash is base accuracy 80%. The fog modifies the accuracy of the move by a factor of 60%, meaning the accuracy is 80% × 60% = 48%.

Minimise being used twice means an evasiveness of +2 (it only raised the evasion by 1 stage in gen 4), which is effectively multiplying the accuracy by 60% yet again. The formula is:

base accuracy × (accuracy - evasiveness)

with any extra effects (e.g. fog) applied to the base accuracy.

The 48% accuracy in addition to ×60% from minimise results in a 28.8% chance to hit. Not so lucky after all, and sumwun was correct.

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