This is related to the famous Focus Energy glitch. I think it's interesting at the very least considering how much Critical Hits shape the RBY metagame.
According to Bulbapedia (http://bulbapedia.bulbagarden.net/wiki/Focus_Energy_(move) ), Focus Energy was intended to multiply the crit ratio by 4, but the glitch makes it be quartered instead.
The way the Critical Hit formula is structured in the games can be summed up to something like this:
(the crit ratio is base speed/2 to this point)

Check for Focus Energy
Has Focus Energy been used? If so, jump to Used
(if not used) Multiply crit ratio by 2 (bit level left shift)
Jump to NotUsed
Used : Divide crit ratio by 2 (bit level right shift) ; fallthrough to NotUsed
NotUsed : (...)
(finally there is another divide by 2, or a multiply by 4 for high crit moves instead)

Click to expand...

Now, if they only made a mistake on the shift that belongs to when Focus Energy is used, we would have two left shifts and the crit chance would be the same (multiply by 2) regardless of whether Focus Energy had been used or not. This wouldn't make much sense to me, since it would mean that Focus Energy would've been intended to do... nothing.
I used to think that they may have missed the two shifts (the one for Focus Energy used and the one for Focus Energy not used), but it looks more probable that they just missed the jumps for whatever reason. Anyway, it seems likely to me that the glitch also involved the non focus energy crit ratio, but since a higher crit ratio than intended doesn't look like a glitch, it never went noticed. Another thing to take into account is that the crit ratio was reduced in the next generation and Pokemon went to crit over less than half the times on average (6.25%).
I made a similar thread in Pokecommunity (http://www.pokecommunity.com/showthread.php?p=7919304 ) but not many people replied anyway. You can find the detailed code there, but if someone in Smogon is familiar with assembly and can take hsi/her own conclusions, I'd like to hear what he/she thinks about this. In general though, I thought this was interesting enough to share considering the impact of critical hits in competitive play.
Last edited: Dec 30, 2013