While going trough the data file which contained the filenames of all trophies in the game, I stumbled upon some trophies in Super Smash Bros. Brawl that were never implemented. Here's the complete list:
CaptainfalconR2
CaptainR1
DededeR2
Diddykongoriginal
DiddyR2
Donkeyjr
Donkeykongoriginal
DonkeykongR2
DreadKong
FalcoR2
Firesting
LectureKikki
LucarioR2
Luigi
LuigiR2
MarioR2
MiteG
MiteR <- Refferenced
MiteY
PikachuR2
PitR2
PoketrainerR2
PurinR2
SheikR2
SnakeR2
SzerosuitR2
ZeldaR2
I'll try to explain some of these trophies.
CaptainfalconR2, DededeR2, DiddyR2, DonkeykongR2, FalcoR2, LucarioR2, LuigiR2, MarioR2, PikachuR2, PitR2, PoketrainerR2, PurinR2, SheikR2, SnakeR2, SzerosuitR2, ZeldaR2
These were supposed to be either alternate trophies or intended trophies. At least this is true for Luigi. Remember that in Subspace Emissary, Luigi's trophy didn't match the actual trophy and actual artwork? Well, LuigiR2 indeed is the exact same pose described in the Subspace Emissary. It could be that you were suppose to be able to catch these trophies during the Subspace Emissary.
CaptainR1, Luigi
These two are almost exactly the same as the ones implemented in the game. In fact, as of yet I haven't spotted any differences.
Diddykongoriginal, Donkeykongoriginal
Much like Fox and Falco, both the Kongs were probably supposed to have retro trophies. Oddly enough, they do appear to have both preview icons and mini-renders, so they were this close to being implemented in the game.
MiteG, MiteR, MiteY
It's possible that you were originally supposed to be able to catch a trophy of all three Mites individually. There is a refference to the red Mite, but it hasn't been featured in the game itself.
Other trophies
Donkeyjr - Donkey Kong Jr. (Donkey Kong Jr.)
DreadKong - Dread Kong (Donkey Kong: Jungle Beat)
Firesting - Fire Stingray (F-Zero series)
LectureKikki - ???
Some other small tidbits
There were also some other things discovered while browsing trough the trophies. This section might get some more updates later on.
Apparently the CDs were supposed to have at least three different prints.
CaptainfalconR2
CaptainR1
DededeR2
Diddykongoriginal
DiddyR2
Donkeyjr
Donkeykongoriginal
DonkeykongR2
DreadKong
FalcoR2
Firesting
LectureKikki
LucarioR2
Luigi
LuigiR2
MarioR2
MiteG
MiteR <- Refferenced
MiteY
PikachuR2
PitR2
PoketrainerR2
PurinR2
SheikR2
SnakeR2
SzerosuitR2
ZeldaR2
I'll try to explain some of these trophies.
CaptainfalconR2, DededeR2, DiddyR2, DonkeykongR2, FalcoR2, LucarioR2, LuigiR2, MarioR2, PikachuR2, PitR2, PoketrainerR2, PurinR2, SheikR2, SnakeR2, SzerosuitR2, ZeldaR2
These were supposed to be either alternate trophies or intended trophies. At least this is true for Luigi. Remember that in Subspace Emissary, Luigi's trophy didn't match the actual trophy and actual artwork? Well, LuigiR2 indeed is the exact same pose described in the Subspace Emissary. It could be that you were suppose to be able to catch these trophies during the Subspace Emissary.
CaptainR1, Luigi
These two are almost exactly the same as the ones implemented in the game. In fact, as of yet I haven't spotted any differences.
Diddykongoriginal, Donkeykongoriginal
Much like Fox and Falco, both the Kongs were probably supposed to have retro trophies. Oddly enough, they do appear to have both preview icons and mini-renders, so they were this close to being implemented in the game.
MiteG, MiteR, MiteY
It's possible that you were originally supposed to be able to catch a trophy of all three Mites individually. There is a refference to the red Mite, but it hasn't been featured in the game itself.
Other trophies
Donkeyjr - Donkey Kong Jr. (Donkey Kong Jr.)
DreadKong - Dread Kong (Donkey Kong: Jungle Beat)
Firesting - Fire Stingray (F-Zero series)
LectureKikki - ???
Some other small tidbits
There were also some other things discovered while browsing trough the trophies. This section might get some more updates later on.
Apparently the CDs were supposed to have at least three different prints.