Stat Boosting Moves in Competitive Play

As you know, some moves can change stats during battle, raising them and lowering them as part of the effect. In-battle stat modifiers multiply specific stats by a certain amount, meaning that a higher starting stat will have a bigger change. For each stat, there are six stages of increase, and six stages of decrease. The six stages of increase are x1.5, x2.0, x2.5, x3.0, x3.5, and x4.0. The six stages of decrease are 2/3, 1/2, 2/5, 1/3, 2/7, and 1/4. Or in other words, to calculate on how much a stat booster would boost your pokemons' stat, refer to this:

+6 Stage = 8/2 = x4
+5 Stage = 7/2 = x3.5
+4 Stage = 6/2 = x3
+3 Stage = 5/2 = x2.5
+2 Stage = 4/2 = x2
+1 Stage = 3/2 = x1.5
0 Stage = 2/2 = x1.0
-1 Stage = 2/3 = x0.66
-2 Stage = 2/4 = x0.5
-3 Stage = 2/5 = x0.4
-4 Stage = 2/6 = x0.33
-5 Stage = 2/7 = x0.28
-6 Stage = 2/8 = x0.25

Of course, as this thread will focus on the discussion of each of these opportunities to increase or decrease a pokemon's stat, it will refrain from focusing on banned moves such as Acupressure. Now, first, moves/abilities can increase on each of the pokemon's individual stat: Attack, Defense, Special Attack, Special Defense, and Speed.

Attack - User

• Belly Drum +6 Attack (halves HP)
• Bulk Up +1 Attack
• Curse +1 Attack
• Coil + 1 Attack
• Dragon Dance +1 Attack
• Growth +1 Attack
• Hone Claws +1 Attack
• Howl +1 Attack
• Meditate + 1 Attack
• Sharpen +1 Attack
• Shell Smash +2 Attack
• Shift Gear +1 Attack
• Swords Dance +2 Attack
• Work Up +1 Attack

Attack - To opponent

• Charm -2 Attack
• Featherdance -2 Attack
• Memento -2 Attack
• Swagger +2 Attack, but causes confusion
• Tickle - 1 Attack
• Growl - 1 Attack

Defense - User

• Acid Armor +2 Defense
• Barrier +2 Defense
• Bulk Up +1 Defense
• Cosmic Power +1 Defense
• Cotton Guard +3 Defense
• Defend Order +1 Defense
• Defense Curl +1 Defense
• Harden +1 Defense
• Iron Defense +2 Defense
• Shell Smash -1 Defense
• Withdraw +1 Defense

Defense - To opponent

• Leer -1 Defense
• Screech -1 Defense
• Tail Whip -1 Defense
• Tickle -1 Defense

Special Attack - User

• Calm Mind +1 Special Attack
• Growth +1 Special Attack
• Nasty Plot +2 Special Attack
• Shell Smash +2 Special Attack
• Quiver Dance +1 Special Attack
• Tail Glow +3 Special Attack
• Work Up +1 Special Attack

Special Attack - To opponent

• Captivate -2 Special Attack
• Flatter +2 Special Attack, causes confusion
• Memento -2 Special Attack

Special Defense - User

• Amnesia +2 Special Defense
• Calm Mind +1 Special Defense
• Cosmic Power +1 Special Defense
• Defend Order +1 Special Defense
• Quiver Dance +1 Special Defense
• Shell Smash -2 Special Defense

Special Defense - To Opponent

• Fake Tears -2 Special Defense
• Metal Sound -2 Special Defense

Speed - User

• Agility +2 Speed
• Autotomize +2 Speed
• Curse -1 Speed
• Dragon Dance +1 Speed
• Quiver Dance +1 Speed
• Rock Polish +2 Speed
• Shell Smash +2 Speed
• Shift Gear +2 Speed
• Tailwind +2 Speed (for everyone in your party for 3 turns)

Speed - To Opponent

• Cotton Spore -2 Speed
• Scary Face -2 Speed
• String Shot -1 Speed

I might of forgotten some, but yeah. Now that's the end of the overview, let's hear what you think. Which stat-boosting moves do you normally use in competitive play? Which stat boost move would you say is the absolute best move to use in competitive play? What pokemon would you say that needs certain stat boosting moves to improve it's sweeping potential? (eg. Some people miiight want Dragon Dance on Garchomp or Flygon). When would you say is the best time for a pokemon to use a stat-boost move? What other thoughts would you like to share about stat-boosting moves?

Wait isn't Tail glow supposed to be +3?
Tail Glow:
drastically raises the sp. Atk stat.
Raises the user's Sp. Atk by three stages.