As you may or may not know, Nixhex and I compiled a bunch of shadow boosts for the Shadow pokemon in
this guide. Well, in looking at the article, you should notice that some of the mons are missing their boosts in HP/Spe, and ALL of them are missing them for Atk/SpA. This discussion is meant to remedy that; I (with Nixhex's approval) am setting off the call for all XD resetters to help out with this project.
Now onto how to go about doing this task:
Smogon's damage calculator:
http://www.smogon.com/calc/
Serebii's shadow moves list:
http://www.serebii.net/attackdex/shadow.shtml
List of physical-based shadow moves:
Shadow Blitz
Shadow Rush
Shadow Break
Shadow End
List of special-based shadow moves:
Shadow Wave
Shadow Rave
Shadow Storm
Shadow Fire
Shadow Bolt
Shadow Chill
Shadow Blast
Note: Shadow Wave, Rave, and Storm hit both of your mons, so their Base Power may or may not be affected by the 75% damage output of multi-target moves (unconfirmed)
Use the above links to compare how much damage the mons in the XD article do versus how much they SHOULD do (you can adjust the attack value by adding EVs until it matches the damage a shadow mon does to your pkmn). Shadow moves
do not get STAB (confirmed), so factor that in when using smogon's damage calculator.
Still don't get how to do it? I'll give you an example, using Dodrio.
example
Dodrio's only damaging shadow move is shadow blitz, which has 40 base power. We're going to be checking it against my lv36 Primeape, which has 102 hp / 56 def. these values are below 31 IVs so we drop the IVs until they match what I have in my game.
When I tested vs. dodrio, the wingless bird did 50 hp damage to primeape when it had 91 attack (I know this because I caught it afterwards). So, lets input everything into the calc.
It turns out that a 91 attack dodrio vs 102 hp / 56 def Primeape does 34-42 hp damage with a 40 Psychic Physical move under normal circumstances (since shadow moves don't get stab, yet they are SE on normal mons, this is what we use to mimic a shadow move). That's a far cry from 50 damage, so let's input evs into dodrio's attack until we DO hit 50 hp damage.
---
Well, in order to do 50 hp damage to primeape, dodrio needs a minimum of 108 attack, or a +17 shadow boost. Yikes.
Anyways, that's how you do it; see how much damage a shadow mon does, catch it, then compare and confirm.
Remember, especially on attack and special attack, shadow boosts will not be constants (in most cases, since apparently GF wants to fib good IVs), so the more data we gather, even if they are in ranges, the better.
This by no means needs to get done anytime soon, but any and all help gathering boosts is appreciated :)
List of cataloged boosts found (that aren't in the guide already):
Poochyena - +1
Duskull - +3
Mawile - +3
Natu - +3
Lunatone - +3
Hypno - +3
Sableye - +3
Dodrio - +3
Banette - +2
Magmar - +3
Pinsir - +3
Rapidash - +1
Lickitung - +3
Scyther - +3
Chansey - +3
Solrock - +3
Swellow - +3
Electabuzz - +3
Snorlax - +3
Mr. Mime - +3
Salamence - +1
Marowak - +3
Lugia - +3
Rhydon - +1
Moltres - +0
Exeggutor - +1
Tauros - +1
Articuno - +0
Zapdos - +0
Dragonite - +2