unlockable events

Co-op Events 9 to 13: Unlock R.O.B. and successfully complete the Subspace
stage in SSE (Subspace Emissary) mode.

Co-op Events 14 to 20: Successfully complete ten Co-op events and unlock all
hidden characters.

Co-op Event 21: Successfully complete all 20 Co-op events.

Events 11 to 20: Successfully complete five of the first ten events.

Events 21 to 28: Unlock R.O.B. and successfully complete the Subspace stage
in SSE (Subspace Emissary) mode.

Events 29 to 40: Unlock all hidden characters.

Event 41: Successfully complete all 40 events

Cheats & Easter Eggs

Easy way to unlock charaters-


STEP 1: go to special brawl mode
STEP 2: choose stamina mode
STEP 3: choose your favorite character
STEP 4:change your number to 10 or more and the CPU'S number to 1
STEP 5:every time the fight ends it will count as one match you can just keep repeating the same process for new characters to appear

Pokemon Stadium and Fish Images:

 

When on Pokemon Stadium 2 (the one with the snow area with the shack), wait until it becomes the snow area, pause the game and look at the inside of the shack on the right side. You should notice a cute kitten picture, and, on the roof, there appears to be the imprint of a fish.

Star Fox Conversations:

If you're playing on Lylat Cruise with two of the three characters from the Star Fox series (Fox, Falco, or Wolf), you can have a conversation between characters. Press down repeatedly on the d-pad (so long as your taunts are mapped to the d-pad) during the battle, and the conversation should occur. This can only happen on the Lylat Cruise stage, and only with two of the three characters from the Star Fox series on that stage at one time.

Snake's Codec:
Here's a really interesting feature to the game that can only be executed by Snake while playing on his stage, Shadow Moses Island. If you have your taunts set to the d-pad on either the Gamecube controller or the Wii controller, press down on the d-pad repeatedly. This must be done extremely fast.
If executed properly, Snake will take a knee and get on his Codec, where he'll speak with familiar characters from the Metal Gear Solid series, including Otacon, Colonel Campbell, and the like. You'll have a completely unique, often humorous conversation with the person on the other end of the Codec depending on who you're fighting. That's right -- there are completely unique conversations for each character, including character variants (Shiek, Zero Suit Samus, the various Pokémon). Give it a try!
Additionally, if Snake is killed when using the Codec, another interesting sequence occurs.

Stages

These are the stages that can be unlocked and how to be unlocked

75m - Play as DK 20 times

Big Blue (Melee) - Play as Captain Falcon 10 times

Flat Zone 2 - Unlock Mr. Game & Watch

Green Greens (Melee) - Play as Kirby 20 times

Green Hill Zone - Unlock Sonic

Hanenbow - Complete Event Match #28

Jungle Japes (Melee) - Fight in VS. Mode 10 times

Luigi's Mansion - Fight with Luigi in VS. Mode 3 times

Mario Bros. - Complete Event Match #19

Pirate Ship - Unlock Toon Link

Pokémon Stadium (Melee) - Fight in Pokémon Stadium 2 10 times in VS. Mode

Spear Pillar - Complete Event Match #25

Music

Here are all of the songs that can be unlocked in the game and how to unlock them

3D Hot Rally Title - Complete Target Level 5

Ai no Uta - Get a combined distance of 37,500 in Home Run Contest

Clu Clu Land - Hit a home run of at least 1,200 feet during a Home Run Contest

Dream Chaser - Play ten VS. matches on Port Town

Excite Truck - Complete Target Level 2 in under nineteen seconds

Fire Field - Complete Event Match #24

Frozen Hillside - Play ten VS. matches on Halberd

Great Temple - Complete Event Match #33 on difficult difficulty

HIS WORLD - Play ten VS. matches on Green Hill Zone

Icicle Mountain - Complete Classic Mode on normal difficulty

Ike's Theme - Find Ike in the Subspace Emissary

King Dedede's Theme - Complete Event Match #15

Legendary Air Rider Machine - Complete Event Match #13

Mach Rider - Defeat fifty enemies in Endless Multi-Man Brawl

Menu 2 - Unlock all thirty-five characters

Metroid Ending - Play ten VS. matches on Norfair

Metroid Prime 2 - Play ten VS. matches on Frigate Orpheon

Mountain Forest - Complete Event Match #18 on difficult

Multi Man Melee - Beat a 100-person brawl in four minutes

O² - Gather at least 5,000 Coins during Coin Matches

Pokémon Center - Acquire 200 different stickers

Power-Hungry Fool - Play ten VS. matches on Castle Siege

Princess' Castle - Unlock all stages from SSB Melee

Road to Viridian City - Complete Event Match #8

Snake Eater - Play fifteen VS. matches on Shadow Moses Island

Song of Storms - Complete Event Match #37

Staff Credits - Complete Classic Mode on hard difficulty

Star Fox Assault Theme - Complete Event Match #38 on hard difficulty

Star Wolf - Complete Event Match #38

Super Mario 64 Theme - Play VS. mode for fifty hours

Super Mario Underwater - Play ten VS. matches on Mario Bros.

Tal Tal Heights - Complete All-Star Mode on easy difficulty

unlockable charcters

Ness-
1)unlock in story mode
2)fight in 5 matches

Marth-
1)finish classic mode with any character
2)fight 10 matches
3)unlock in story mode

Luigi-
1)unlock in story mode
2)fight 22 matches
3)clear classic mode with no continues in any level

Falco-
1)unlock in story mode
2)finish the 100  man brawl
3)fight 50 matches

Captain Flacon-
1)unlock in story mode
2)clear classic mode under 12 minutes
3)fight 70 matches

Lucario-
1)unlock in stroy mode
2)complete 5 target tests
3)fight 100 matches

Snake-
1)play on shadow moses island 15 times
2)unlock in story mode
3)fight 130 matches

R.O.B-
1)collect 250 trophies
2)unlock in story mode
3)fight 160 matches

Ganondorf-
1)finish classic mode with Zelda or Link
2)unlock in story mode
3)fight 200 matches

Mr. game and Watch-
1)complete 30 target tests with any character
2)unlock in story mode
3)fight 250 matches

Sonic-
1)clear classic mode with 10 dfinish ifferent charatcters
2)play for a total of 10 hours
3)unlock in story mode
4)fight 300 matches

Jigglypuff-
1)compete classic mode with any character
2)finish event #20
3)unlock in story mode
4)fight 350 matches

Toon Link-
1)finish the story mode and then finish the classic mode
2)fight 400 matches

Wolf-
1)finish story mode then complete boss battles with fox or falco
2)fight in 450 matches
1)finish classic mode with any character