Buff

A buff is a term used to describe the improvement of a character (or aspect of a character), either through updating a game or by releasing a sequel. The opposite term is "Nerf".

A good example of a character being buffed is Zelda in Brawl, where she has quicker, stronger attacks, in strong contrast to her attacks in Melee. another example is kirby has completely regained his power having increased speed and power

Characters who had attributes buffed from SSB to SSBM

 * Captain Falcon: His air speed was increased. Was given a new forward air, the Knee Smash, a devastating horizontal finisher (his SSB64 forward air was made his neutral air in Melee). All of his smash attacks were changed and made more powerful (down smash is now a much more viable finisher and move in general).  Down tilt has better range and combo ability.  Falcon Kick now restores his midair jump if previously used.
 * Donkey Kong: His Giant Punch is faster and has less ending lag, his air speed is much faster, and he is a faster character overall; uair can now combo opponents.
 * Fox: He now has the ability to infinite shine, wave shine, shine jump cancel; he has faster movement and attacks; his attacks are stronger; and he has an additional recovery option with Fox Illusion.
 * Jigglypuff: Rest is much stronger; Pound is much faster; all jumps now give height; increased reach in its attacks; its air speed is faster.
 * Kirby: Forward tilt is stronger, can now Kirbycide. Also his swallow buffed due to the better self destruct method and having more characters to choose from.
 * Link: His recovery is much better (from arguably the worst to one of the best); he is a faster character overall. Better SHFFL so he can combo easier and his air game is improved.
 * Luigi: Has a new fair with much more knockback; his dair has also changed (slightly) with increased knockback and it can now meteor smash like Mario's new fair.
 * Mario: Has a new fair, which has the ability to Meteor Smash; he has a reflector in his Cape; he has also gained the ability to chain throw opponents.
 * Ness: He now has a very strong projectile in PK Flash.
 * Pikachu: Its down smash can now combo opponents; has a new special in Skull Bash that can be a powerful KO move as well as aid in recovery.
 * Samus: Her recovery was improved, has a new very effective projectile in the Smash Missiles; she is also a faster character overall.
 * Yoshi: His recovery was improved.

Characters who had attributes buffed from SSBM to SSBB

 * There was an overall buff to shielding and dodging: faster shields (both in putting up and dropping), longer perfect shield window, faster sidesteps (around half with additional multiple IASAs), faster rolls, and infinite air dodges. This, combined with an overall reduction of hitstun, has made Brawl a much more defense based game than its predecessors.
 * Bowser: Fire Breath now can be aimed up and down, recharges faster, and has longer range; F-Tilt has better range; Bowser Bomb falls faster, is much stronger (can reliably KO under 100%), and also hits during the rising animation when used on the ground; U-Smash has longer range; increased jump height; increased air speed. Faster overall.
 * Captain Falcon: Falcon Punch now charges faster, Raptor Boost now is easier to use for both attacking and recovery, Falcon Dive can grab foes on a ledge, making him harder to edgehog. Jab, down smash, up air, and up tilt received very minor buffs (the first two have slightly better range and the last two are slightly faster).
 * Donkey Kong: Fully charged Giant Punch now has super armor frames; Headbutt is faster and stronger; D-Tilt and F-Tilt (when angled down) now trip; Spinning Kong travels slightly farther (both horizontally and vertically) and has super armor frames (when used on the ground); U-Smash can hit grounded opponents; F-Smash and D-Smash have much higher knockback; Hand Slap has more range and damage; better approach options; increased shield size. Several other attacks have slightly increased range, speed, and/or power, making him an overall better character.
 * Ice Climbers: Both can grab ledges simultaneously; Belay is a tether recovery if near the ledge; lone Belay gives slight distance; the partner's AI is increased.
 * Falco: U-smash and u-air are much stronger. Falco Phantasm is faster and travels farther, making it a better attack and recovery move. F-tilt has better range. Several attacks were changed and given more range and disjointedness, such as jab, f-smash and his Reflector.  N-air is better at setups.  Can now SHDL.  Down throw now chain throws and is one of the best chain-throws in the game due to its versatility. He is also less vulnerable to combos and chain-throws (he is perhaps, the fast-faller least vulnerable to chain-throws).
 * Kirby: Improved throws; increased priority; much stronger smashes; slightly faster air speed (still slow); Swallow can eat items; increased range; throws are now inescapable. Faster and much more powerful overall. He is on par with Mr.G&W for being the most buffed character in Brawl.
 * Luigi: F-Smash has much higher knockback; B-Throw is stronger; Green Missile can be charged infinitely, and misfire travels a shorter distance to prevent SDs; Vertical momentum is carried into Green Missile and Luigi Cyclone rather than just stopping and the attack executing; much easier to move vertically with Luigi Cyclone; Super Jump Punch is more like its SSB counterpart and covers more horizontal distance when helpless; lateral air speed is generally faster (but is still the second-slowest); Down Taunt has higher set knockback. Stronger overall.
 * Mario: Super Jump Punch has more knockback; Down air (which is now the Mario Tornado) is faster and has more knockback than his Melee D-air; Cape carries any momentum with it, allowing for new techniques such as the Cape Glide; Cape reverses foes' momentum.
 * Marth: Dolphin Slash improved; Counter damage now scales with the countered attack; Dancing Blade is faster and easier to perform. His tipped attacks are generally stronger and with much higher base knockback.
 * Mr. Game & Watch: Increased priority; larger shield; Fire now produces a parachute (instead of his N-Air), and he can attack after using it; Oil Panic can cancel all knockback dealt to him; larger sweetspot and stronger sourspot in D-Smash. Much better range with D-tilt. Even though his overall speed didn't change, brawl's gameplay slowed down, putting him at a less disadvantage than melee. He is on par with Kirby for being the most buffed character in Brawl.
 * Ness: D-Air has better range and power; Dash Grab has better range and is faster; PK Thunder 2 has less lag and is much more powerful; U-Smash and D-Smash now have KO potential; PK Flash charges slightly faster and is easier to control; PK Fire is faster; B-Throw is slightly more powerful. Stronger overall.
 * Pikachu: Thunder has less ending lag and is stronger when it connects with Pikachu; increased grab range (no longer the shortest); Quick Attack can now be used to perform a QAC. D-smash is much better at KOing and racking up damage. He is also capable of performing large chain-throws (he is one of the four premier chain-throwers in Brawl).
 * Sheik: F-tilt can now lock most characters, Chain moves more freely and can be used as a tether recovery, Vanish has less lag and is stronger in terms on knockback, Needle Storm now stops charging when it is fully charged (instead of having to press Z to save them).
 * Yoshi: Egg Toss can be used for recovery; several tilts and aerials improved; faster air speed (ranked the best in the game).
 * Zelda: Din's Fire now has larger hitbox, is much faster and stronger, and has less ending lag; Farore's Wind creates an explosion upon reappearing; U-Air is a much better finisher; sweetspotted aerials have increased in knockback; slightly increased dash speed; faster grab. Stronger overall.