Oh, nice resource. I made a Stat Boost Tier list, for reference.
Kill Everything Tier
Shell Smash 15 0 — Raises user's Attack, Special Attack, and Speed by two stages. Lower user's Defense and Special Defense by one stage.
Use Nothing Else Tier
Butterfly Dance 20 0 — Raises the user's Special Attack, Special Defense, and Speed by one stage each.
Snake Coil 20 0 — Raises the user's Attack, Defense, and accuracy by one stage each.
Cotton Guard 10 0 — Raises the user's Defense by three stages.
Tail Glow 20 0 — Raises the user's Special Attack by three stages.
Gear Change 10 0 — Raises the user's Attack by one stage and its Speed by two stages.
Minimize 20 0 — Raises the user's evasion by two stages.
Also Usable Tier
Cosmic Power 20 0 — Raises the user's Defense and Special Defense by one stage.
Swords Dance 30 0 — Raises the user's Attack by two stages.
Amnesia 20 0 — Raises the user's Special Defense by two stages.
Growth 40 0 — Raises the user's Attack and Special Attack by one stage (two stages, in Sunlight)
Agility 30 0 — Raises the user's Speed by two stages (Attack boosts increases the power of self-damage moves)
Situational Tier
Acupressure - 30 - Raises one of a friendly Pokémon's stats at random by two stages.
Body purge 15 0 — Raises the user's Speed by two stages and halves the user's weight. (could be good or bad respectively)
Curse 10 0 - Ghosts pay half their max HP to hurt the target every turn. Others decrease Speed but raise Attack and Defense (Speed drop can be used beneficially)
Stockpile 20 0 - Stores energy up to three times for use with Spit Up and Swallow
Double Team 15 0 — Raises the user's evasion by one stage. (Stomp and Hard Roller do less damage)
Dragon Dance 20 0 — Raises the user's Attack and Speed by one stage. [Gear Change denies you +6 Attack against Pressure]
Defense Curl 40 0 — Raises user's Defense by one stage. (Rollout bonus)
Charge 20 0 — Raises the user's Special Defense by one stage. User's Electric moves have doubled power next turn.
Skull Bash 15 100 100% - Raises the user's Defense by one stage. User charges for one turn before attacking.
Outclassed Tier
Calm Mind 20 0 — Raises the user's Special Attack and Special Defense by one stage. [Butterfly Dance]
Bulk Up 20 - Raises the user's Attack and Defense by one stage. [Snake Coil]
Nasty Plot 20 0 — Raises the user's Special Attack by two stages. [Tail Glow]
Work Up 30 0 — Raises the user's Attack and Special Attack by one stage each. [Growth is better in Sunlight]
Hone Claws 15 0 — Raises the user's Attack and accuracy by one stage. [Snake Coil]
Acid Armor 40 0 — Raises the user's Defense by two stages. [Cotton Guard]
Barrier 30 0 — Raises the user's Defense by two stages.
Iron Defense 15 0 — Raises the user's Defense by two stages.
Defend Order 10 0 — Raises the user's Defense and Special Defense by one stage. [Cosmic Power has more PP]
Rock Polish 20 0 — Raises the user's Speed by two stages. [Agility has more PP]
What Are You Doing tier
Sharpen 30 0 — Raises the user's Attack by one stage.
Howl 40 0 — Raises the user's Attack by one stage.
Meditate 40 0 — Raises the user's Attack by one stage.
Harden 30 0 — Raises the user's Defense by one stage.
Withdraw 40 0 — Raises the user's Defense by one stage.
I may have missed some worth mentioning, in which case please inform.
