Alright, kids, it's time for...
STAT ALTERING 101
Thanks to Raichu, I went off in search of an answer to her stat-alteration question and discovered how it really works! This knowledge is bound to come in handy. Here's how it works:
For Attack, Defense, Special Attack, Special Defense and Speed, it works on a base of 2. Check this out:
-6 = 2/8
-5 = 2/7
-4 = 2/6
-3 = 2/5
-2 = 2/4
-1 = 2/3
0 = 1
+1 = 3/2
+2 = 4/2
+3 = 5/2
+4 = 6/2
+5 = 7/2
+6 = 8/2
Notice the pattern? (I know those fractions could be simplified, but it's easier to visualize this way.)
The negative side of that scale represents a decrease in value, while the positive side shows an increase in the value. You can alter a stat by up to six stages in either direction, but no more (METAPOD's DEFENSE won't go any higher!)
For example, if you used the move Harden, your Pokémon's Defense stat will be +1, meaning 150% of what it used to be. If you used Screech, the foe's Defense stat will drop by 2, putting it at -2, or half of its original value.
Curse lowers your Speed to -1 (2/3 of what it was) and raises both your Attack and Defense to +1 (3/2). Belly Drum raises your Attack to its maximum stage, +6, and your Attack power is four times higher! You thought Hyper Beam had 150 Base Power? You thought that was good enough? Well, a Snorlax, after using Belly Drum, and with the benefit of Same Type Attack Bonus, puts Hyper Beam's power at freakin' 900! And Snorlax already has such high Attack stats, too.
Evasion works in a similar way, but on a scale of 3, not 2.
-6 = 9/3
-5 = 8/3
-4 = 7/3
-3 = 6/3
-2 = 5/3
-1 = 4/3
0 = 1
+1 = 3/4
+2 = 3/5
+3 = 3/6
+4 = 3/7
+5 = 3/8
+6 = 3/9
(This scale shows the changes relative to how your Pokémon benfit, with the negative side being your ability to evade, and the positive side the enemy's ability to strike you.)
If you use the ever-popular Double Team once, which raises your evasion rate by +1, you are 3/4 as likely to be hit by the enemies attack. A move like Sand Attack, which lowers the opponent's accuracy to -1, makes you 4/3 as likely to dodge the attack.
Again, there's a maximum of six steps to take in either direction. You cannot raise your evasion to more than 9/3, and you cannot lower the foe's accuracy to more than 3/9. However...
You CAN raise both your EVADE and the foe's ACCURACY. Say you used six Mud-Slaps and six Minimizes, your chances are (3/9)*(3/9) = 3/27, which is much higher than you could get with just one of the two moves. Then again, are you really going to spend twelve turns leading up to this?
You can get greater advantages with Attack, Defense, Special Attack, Special Defense and Speed in the same way, by raising your Defenses and lowering the foe's Attacks, or by raising your Speed and lowering the foe's.
Capiche?
