Okay, I'm tired of it all, seeing 20 thousand of these. So, I'll get it started
I don't have brawl on hand at the moment, but I'll update this post. When I can I'll start copying it from the ones I've unlocked from the Collectables menu options
Characters
*All characters can be unlocked in SSE
Captain Falcon - Beat Classic in 12 minutes or less OR 70 VS matches
Falco - Beat 100-man Brawl OR 50 VS matches
Ganondorf - Clear Classic on Hard with Link or Zelda OR Play 200 VS Matches
Jigglypuff - Complete Classic Mode with any character other than Ike or Complete 20 Events after beating SSE or 350 VS matches
Lucario - Complete 5 Target Tests with any character or 100 VS matches
Luigi - Complete Classic Mode on Easy without continues or 22 VS matches
Marth - Finish Classic on any difficulty OR 10 VS matches
Mr. Game & Watch - Beat Classic mode with Every character (Starting Roster?) or 250 VS matches
Ness - Reflect ten projecticles OR 5 VS matches
R.O.B. (Robot) - Get 250 different Trophies OR 150 VS matches
Snake - 15 matches on Shadow Moses Island OR 130 VS matches
Sonic - Run 30,000ft OR 300 VS Matches
Toon Link - Beat the Classic mode after beating SSE OR 400 VS matches
Wolf - Unlock in SSE (in the stage "The Ruins" skip the first door you pass when being lowered in to the pit. Instead enter the second door at the bottom) or 450 VS matches
Stages
75m - Brawl as Donkey Kong 20 times
Big Blue (Melee) - Brawl as Captain Falcon 10 times
Electroplankton Stage - Complete Event #28
Flat Zone 2 - Unlock Mr. Game & Watch
Great Sea - Unlock Toon Link
Green Greens - Fight as Kirby in VS mode 20 times
Green Hill Zone - Unlock Sonic
Jungle Japes - Play on any Melee stage 10 times in VS Mode
Luigi's Mansion - Use Luigi in brawl 3 times
Mario Bros - Beat Challenge #19
Pokémon Stadium - Play on Pokémon Stadium 2 10 times in VS Mode
Spear Pillar - Clear stage #25 in Event Mode
CDs
02 (Zero Two) Boss Theme (Kirby 64) - Have a total of 5000 coins collected in vs. coin matches
100-Man Melee 1 - Clear 100-Man Brawl under 4 minutes
3D Hot Rally Title - Clear Target Level 5 With Anyone
Bob-Omb Battlefield (Super Mario 64) - Have a total of 50 hours of vs. gameplay
Dream Chaser - Play 10 vs. matches on Port Town
Ending (Metroid) - Play 10 vs. matches on Norfair
Excite Truck - Complete Target Test Lv.2 under 19 seconds with any character
Fire Field - Complete Event #24
Frozen Hillside - Play on the Halberd stage 10 times in VS mode
Goruda - Play 10 vs. matches on Halberd
Great Temple - Complete Event #33 on Difficult
His World - Play 10 vs. matches on Green Hill Zone
His World (Instrumental) Play 10 vs. matches on Green Hill Zone
Ice Climbers (Melee) - Clear Classic Mode on Easy with any character
Ike's Theme - Find Ike in the Subspace Emissary
King Dedede's Theme - Complete Event #15
Kuru Kuru Land - Get a distance of 400m in Home-Run Contest with one character
Legendary Air Rider Machine - Complete Event #13
Love Song (commercial version) - Get a combined distance of 12500m in Home-Run Contest
Mach Rider (melee version) - Defeat 50 alloys in Endless Multi-Man Brawl
Menu 2 - Unlock All 35 Characters
Metroid Prime 2: Multi-Play - Play 10 vs. matches on Frigate Orpheon
Mountain and Forest - Complete Event #18 on Difficult
Peach Castle (Melee) - Unlock all Melee stages
Pokémon Center Collect 200 stickers
Powerhungry Fool - Play 10 vs. matches on Castle Siege
Road to Tokiwa - Complete Event #8
Snake Eater - Play 15 vs. matches on Shadow Moses Island
Song of Storms - Complete Event #37
Staff Credits Music - Clear Classic Mode on Difficult
Star Wolf (Star Fox: Assault) - Complete Event #38 on Difficult
Taru Taru Highlands - Clear All-Star Mode on Easy
Underwater BGM (Super Mario Bros) - Play 10 vs. matches on Mushroomy Kingdom
Trophies
Others
All-Star Mode - Unlock all characters
Boss Battle Mode - Beat SSE
Edit Parts A - Play 10 vs. matches on Stage Builder Stages
Edit Parts B - Create 5 Stages in Stage Builder
Edit Parts C - Create 15 Stages in Stage Builder
Donkey Kong VC - Exceed 10 hours of play time
F-zero VC - Beat SSE having used captain Falcon
Legend of Zelda Ocarina of Time VC - Use Toon Link over 10 times
Super Mario USA VC - Win 5 Regular VS Battles with Peach
Super Mario World VC - Play yoshi's Island (melee) over 3 times
Level 2 (Medium) - Beat Classic Mode twice on Easy or once on Medium
Level 3 (Hard) - Beat Classic Mode twice on Medium or once on Hard
Level 4 (Very Hard) - Beat Classic Mode twice on Hard or once on Very Hard
Level 5 (Intense) - Beat Classic Mode twice on Very Hard or once on Intense
Random Stage Select - Unlock All Stages AND already have Advanced Options
Lime = Verified
Cyan = Unsure
I don't have brawl on hand at the moment, but I'll update this post. When I can I'll start copying it from the ones I've unlocked from the Collectables menu options
Characters
*All characters can be unlocked in SSE
Captain Falcon - Beat Classic in 12 minutes or less OR 70 VS matches
Falco - Beat 100-man Brawl OR 50 VS matches
Ganondorf - Clear Classic on Hard with Link or Zelda OR Play 200 VS Matches
Jigglypuff - Complete Classic Mode with any character other than Ike or Complete 20 Events after beating SSE or 350 VS matches
Lucario - Complete 5 Target Tests with any character or 100 VS matches
Luigi - Complete Classic Mode on Easy without continues or 22 VS matches
Marth - Finish Classic on any difficulty OR 10 VS matches
Mr. Game & Watch - Beat Classic mode with Every character (Starting Roster?) or 250 VS matches
Ness - Reflect ten projecticles OR 5 VS matches
R.O.B. (Robot) - Get 250 different Trophies OR 150 VS matches
Snake - 15 matches on Shadow Moses Island OR 130 VS matches
Sonic - Run 30,000ft OR 300 VS Matches
Toon Link - Beat the Classic mode after beating SSE OR 400 VS matches
Wolf - Unlock in SSE (in the stage "The Ruins" skip the first door you pass when being lowered in to the pit. Instead enter the second door at the bottom) or 450 VS matches
Stages
75m - Brawl as Donkey Kong 20 times
Big Blue (Melee) - Brawl as Captain Falcon 10 times
Electroplankton Stage - Complete Event #28
Flat Zone 2 - Unlock Mr. Game & Watch
Great Sea - Unlock Toon Link
Green Greens - Fight as Kirby in VS mode 20 times
Green Hill Zone - Unlock Sonic
Jungle Japes - Play on any Melee stage 10 times in VS Mode
Luigi's Mansion - Use Luigi in brawl 3 times
Mario Bros - Beat Challenge #19
Pokémon Stadium - Play on Pokémon Stadium 2 10 times in VS Mode
Spear Pillar - Clear stage #25 in Event Mode
CDs
02 (Zero Two) Boss Theme (Kirby 64) - Have a total of 5000 coins collected in vs. coin matches
100-Man Melee 1 - Clear 100-Man Brawl under 4 minutes
3D Hot Rally Title - Clear Target Level 5 With Anyone
Bob-Omb Battlefield (Super Mario 64) - Have a total of 50 hours of vs. gameplay
Dream Chaser - Play 10 vs. matches on Port Town
Ending (Metroid) - Play 10 vs. matches on Norfair
Excite Truck - Complete Target Test Lv.2 under 19 seconds with any character
Fire Field - Complete Event #24
Frozen Hillside - Play on the Halberd stage 10 times in VS mode
Goruda - Play 10 vs. matches on Halberd
Great Temple - Complete Event #33 on Difficult
His World - Play 10 vs. matches on Green Hill Zone
His World (Instrumental) Play 10 vs. matches on Green Hill Zone
Ice Climbers (Melee) - Clear Classic Mode on Easy with any character
Ike's Theme - Find Ike in the Subspace Emissary
King Dedede's Theme - Complete Event #15
Kuru Kuru Land - Get a distance of 400m in Home-Run Contest with one character
Legendary Air Rider Machine - Complete Event #13
Love Song (commercial version) - Get a combined distance of 12500m in Home-Run Contest
Mach Rider (melee version) - Defeat 50 alloys in Endless Multi-Man Brawl
Menu 2 - Unlock All 35 Characters
Metroid Prime 2: Multi-Play - Play 10 vs. matches on Frigate Orpheon
Mountain and Forest - Complete Event #18 on Difficult
Peach Castle (Melee) - Unlock all Melee stages
Pokémon Center Collect 200 stickers
Powerhungry Fool - Play 10 vs. matches on Castle Siege
Road to Tokiwa - Complete Event #8
Snake Eater - Play 15 vs. matches on Shadow Moses Island
Song of Storms - Complete Event #37
Staff Credits Music - Clear Classic Mode on Difficult
Star Wolf (Star Fox: Assault) - Complete Event #38 on Difficult
Taru Taru Highlands - Clear All-Star Mode on Easy
Underwater BGM (Super Mario Bros) - Play 10 vs. matches on Mushroomy Kingdom
Trophies
Others
All-Star Mode - Unlock all characters
Boss Battle Mode - Beat SSE
Edit Parts A - Play 10 vs. matches on Stage Builder Stages
Edit Parts B - Create 5 Stages in Stage Builder
Edit Parts C - Create 15 Stages in Stage Builder
Donkey Kong VC - Exceed 10 hours of play time
F-zero VC - Beat SSE having used captain Falcon
Legend of Zelda Ocarina of Time VC - Use Toon Link over 10 times
Super Mario USA VC - Win 5 Regular VS Battles with Peach
Super Mario World VC - Play yoshi's Island (melee) over 3 times
Level 2 (Medium) - Beat Classic Mode twice on Easy or once on Medium
Level 3 (Hard) - Beat Classic Mode twice on Medium or once on Hard
Level 4 (Very Hard) - Beat Classic Mode twice on Hard or once on Very Hard
Level 5 (Intense) - Beat Classic Mode twice on Very Hard or once on Intense
Random Stage Select - Unlock All Stages AND already have Advanced Options
Lime = Verified
Cyan = Unsure