I cut the thread down to size. This should probably help spiff up the most visited thread on this forum. Just copy and paste, I guess. Give credit to everyone I listed.
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Generally Usable
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Jab: Use of a weak attack to deter an enemy's attack/cancel a projectile.
Shield Dash: Dash and shield. You slide a little with your shield.
Angled Attacks: Angling a F-Tilt or F-Smash with the Control Stick to give it a raised/lowered hitbox. May change hitstun, shieldstun, knockback of the original unangled move.
Charge Cancel: When DK/Samus are charging their Neut B, press Z to cancel it. DK can cancel fully charged punches as well. Pressing left/right during the charging animation makes you dodge roll left/right respectively.
Shield Jump: The basis of Up-B/Up-Smash out of shield. You can jump out of your shield. Yeah.
Shield Drop: Shielding on a drop-through platform, then dropping. Useful mid-dash to drop faster, rather than having to stop.
Low Shield: Holding down while shielding to lower the shield. Stops some low shield pokes.
Sliding Turnaround edgehog: Running and turning as you reach the edge to fall off facing the edge and ledgehogging. Not doable with all characters.
Link's Up-B Turnaround edgehog: Same thing plus a Spin Attack.
http://www.youtube.com/watch?v=E82TNOFtkz0
Infinite Throw Trap: Grab someone with DK, and let them wiggle out. Then grab them again. It comes down to your reaction time vs. theirs.
Epic Turn Slide: Japanese version only. Doable with DK, Yoshi, Fox, Jiggs, Kirby.
http://www.youtube.com/watch?v=-gCsn4EXpIQ
Keyboard Hax Smash DI: Lol. Spam direction key, get out of combo.
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Character Specific
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Mario Bros. Up-B Angling: Hold forward while using Coin Jump Punch/Fire Jump Punch to move further forward. Hold B without direction to move further upwards.
Yoshi's DJC Ledgegrab: Jump off, do whatever, then reverse and double-jump. You can grab the edge if done right.
http://www.youtube.com/watch?v=91hVs34-LCc
B-Move Ledgehog: Cancel a B move into a ledgehog. Works with Ness's PK Thunder and PSI Magnet and Yoshi's Ground Pound and Egg Throw.
Teleport: Jiggs and Samus (and Fox, less noticeable) only. Enter a full dash, turn around then jump to get a 'warp' effect forward. You can use an aerial/B move right out of this technique.
Link's Bomb Recovery: When off the ledge, pull out a bomb during your double jump, lightly throw it under you, then B-Air to hit it. You end up facing away from the edge, so usefulness is limited.
http://www.youtube.com/watch?v=03K-CcYBgTw (Also shows 2x DI)
Kirby's Pivot Sliding Up-B: Found by House. To do it: Dash, wait for it to finish which is about 14 frames, turn, then do an Up+B 20 frames after you decided to do so.
http://www.youtube.com/watch?v=q-njd578Aws
SHDL: Short hop double laser (Fox and Kirby with Fox laser). Involves shooting two (or three in Kirby's case) lasers in a single short hop. First laser usually goes too high, second should hit most foes. Useful for camping, approaches, etc
FHTL: Full hop triple laser.
DJQL: Double jump quad laser. Yeah, I made this one up.
Falcon's Rising Punch: Use of the Falcon Punch as you use your second jump to gain slight vertical and noticeable horizontal distance.
Falling Punch/Pound: Falcon Punch/Pound angled downwards. Sorta useless outside novelty use.
PK Thunder 2: Directing Ness's PK Thunder into him for a lengthy recovery. Very predictable, but still a staple of Ness play.
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General - TAS/Very difficult to implement/silly
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Drop Cancel: TAS only, really.
http://www.youtube.com/watch?v=2TBfiEuzYAc
Taunt Cancel 2: Press Z to cancel certain taunts mid-taunt and go into a shield. Mario's springs to mind.
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Character Specific - TAS/Very difficult to implement
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Falcon Dive Cancel: Cancelling Falcon's Up-B. TAS stuff, but doable with lots and lots of practice, I guess.
http://www.youtube.com/watch?v=vSXStr1DQ9Q
Ness DJC Rush: Pretty new tech, rapidly timed DJCs boost Ness's speed greatly.
http://www.youtube.com/watch?v=UqnHJh7Qyag
Ledge Teleport Feint: Jiggs/Samus only, Fox's isn't long enough, AFAIK. Teleport off a ledge and move back to land back on the ledge.
http://www.youtube.com/watch?v=IEHfk71_HO0
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These two should help the Tier section (which atm has no links, as far as I can see)
Tier List
http://www.smashboards.com/showthread.php?t=250563
Tier Discussion
http://www.smashboards.com/showthread.php?t=241670
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Credit should be given to: Moogle, Platinum Kirby, ant-d, rokimomi, Lovage, Sensei, others who I forget :\
Almost purely re-interpretation. Some was basic stuff, forgotten for some reason.