This page is for documenting the different development leftovers, not including removed zones and text.

Inside Giga-lakitu's ObjectData file BossJugem.arc happens to be the decompiled source for the BTP (Binary Texture Pallete) filetype. DemoEndingBossJugem.dtp was exported from Maya 2008 Service Pack 1 on 17/3/2010. It's full source is here:

<TEX_PAT_INFO>
{
	version	3.150
	filename	W:/wii-mottomario/murata_sho/data/BinaryData/BossJugem/DemoEndingBossJugem
	toolname	Maya
	source	'Maya 2008 Service Pack 1 - (DemoEndingBossJugem.mb)'
	date	2010/3/17
	time	0:56:47
	host	EADMURATAS
	suitable_joint	cull_more	47
	numjoints	30
	numframes	370
	playmode	onetime
	numtexpats	1
	compress_mat	on
}

<TEX_PAT>
{
	index	0
	mat_name	MtJugemEye_v
	tex_index	0
	numtextures	3
	tex_name	BossJugemEye.0
	tex_name	BossJugemEye.1
	tex_name	BossJugemEye.2
	size	371
	pattern	0 0 0 0 0 0 0 0 0 0
	pattern	0 0 0 0 0 0 0 0 0 0
	pattern	0 0 0 0 0 0 0 1 1 1
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 2 2 2 2 2 2 2 2 2
	pattern	2 
}

<TEX_IMG>
{
	index	0
	name	BossJugemBody
}

<TEX_IMG>
{
	index	1
	name	BossJugemClown
}

<TEX_IMG>
{
	index	2
	name	BossJugemEye.0
}

<TEX_IMG>
{
	index	3
	name	BossJugemEye.1
}

<TEX_IMG>
{
	index	4
	name	BossJugemEye.2
}

<TEX_IMG>
{
	index	5
	name	BossJugemShell
}

<TEX_IMG>
{
	index	6
	name	FurBossJugemScarf_vBody
}

<TEX_IMG>
{
	index	7
	name	jugem_lens
}

<TEX_ATTR>
{
	index	0
	image	0
}

<TEX_ATTR>
{
	index	1
	image	1
}

<TEX_ATTR>
{
	index	2
	image	2
}

<TEX_ATTR>
{
	index	3
	image	3
}

<TEX_ATTR>
{
	index	4
	image	4
}

<TEX_ATTR>
{
	index	5
	image	5
}

<TEX_ATTR>
{
	index	6
	image	6
}

<TEX_ATTR>
{
	index	7
	image	7
}

<MATERIAL>
{
	index	0
	name	FurBossJugemScarf_v
	texture0	6
	texture1	-1
	texture2	-1
	texture3	-1
	texture4	-1
	texture5	-1
	texture6	-1
	texture7	-1
}

<MATERIAL>
{
	index	1
	name	MtJugemBody_v
	texture0	0
	texture1	-1
	texture2	-1
	texture3	-1
	texture4	-1
	texture5	-1
	texture6	-1
	texture7	-1
}

<MATERIAL>
{
	index	2
	name	MtJugemClown_v
	texture0	1
	texture1	-1
	texture2	-1
	texture3	-1
	texture4	-1
	texture5	-1
	texture6	-1
	texture7	-1
}

<MATERIAL>
{
	index	3
	name	MtJugemEye_v
	texture0	2
	texture1	-1
	texture2	-1
	texture3	-1
	texture4	-1
	texture5	-1
	texture6	-1
	texture7	-1
}

<MATERIAL>
{
	index	4
	name	MtJugemShell_v
	texture0	5
	texture1	-1
	texture2	-1
	texture3	-1
	texture4	-1
	texture5	-1
	texture6	-1
	texture7	-1
}

<MATERIAL>
{
	index	5
	name	jugem_joint:lens_tex_v
	texture0	7
	texture1	-1
	texture2	-1
	texture3	-1
	texture4	-1
	texture5	-1
	texture6	-1
	texture7	-1
}

<JOINT>
{
	index	0
	name	AllRoot
	ndisplays	6
	display	0
	display	1
	display	2
	display	3
	display	4
	display	5
}

<JOINT>
{
	index	1
	name	Root
	ndisplays	0
}

<JOINT>
{
	index	2
	name	Center
	ndisplays	0
}

<JOINT>
{
	index	3
	name	JointRoot
	ndisplays	0
}

<JOINT>
{
	index	4
	name	Head
	ndisplays	0
}

<JOINT>
{
	index	5
	name	CheekL
	ndisplays	0
}

<JOINT>
{
	index	6
	name	CheekR
	ndisplays	0
}

<JOINT>
{
	index	7
	name	Glasses
	ndisplays	0
}

<JOINT>
{
	index	8
	name	Hear
	ndisplays	0
}

<JOINT>
{
	index	9
	name	LowerLip
	ndisplays	0
}

<JOINT>
{
	index	10
	name	UpperLip
	ndisplays	0
}

<JOINT>
{
	index	11
	name	LegL
	ndisplays	0
}

<JOINT>
{
	index	12
	name	KneeL
	ndisplays	0
}

<JOINT>
{
	index	13
	name	FootL
	ndisplays	0
}

<JOINT>
{
	index	14
	name	LegR
	ndisplays	0
}

<JOINT>
{
	index	15
	name	KneeR
	ndisplays	0
}

<JOINT>
{
	index	16
	name	FootR
	ndisplays	0
}

<JOINT>
{
	index	17
	name	Scarf
	ndisplays	0
}

<JOINT>
{
	index	18
	name	Shell
	ndisplays	0
}

<JOINT>
{
	index	19
	name	SholderL
	ndisplays	0
}

<JOINT>
{
	index	20
	name	ArmL
	ndisplays	0
}

<JOINT>
{
	index	21
	name	WristL
	ndisplays	0
}

<JOINT>
{
	index	22
	name	FingerL
	ndisplays	0
}

<JOINT>
{
	index	23
	name	ThumbL
	ndisplays	0
}

<JOINT>
{
	index	24
	name	SholderR
	ndisplays	0
}

<JOINT>
{
	index	25
	name	ArmR
	ndisplays	0
}

<JOINT>
{
	index	26
	name	WristR
	ndisplays	0
}

<JOINT>
{
	index	27
	name	FingerR
	ndisplays	0
}

<JOINT>
{
	index	28
	name	ThumbR
	ndisplays	0
}

<JOINT>
{
	index	29
	name	Tail
	ndisplays	0
}

Super Mario Galaxy 2's /StageData/ folder contains the level map, scenario and many other files for each galaxy. What is interesting however, is that it's got many empty folders inside with unused entries.

Here's the full list of zones:

AncientExcavationTest02Galaxy
AndoBonusTest
AndoPlanetJumpTest
AndoSwimTest
AndoYoshi2Test
AndoYoshiStage
AoyagiTest
AoyagiTestMore
BarrelGravityConversionPlanetZone
BonusAZone
BossBussunZone
BossParadeGalaxy
BussunTestZone
Chaos2DAutoAthleticsZone
Chaos2DBegomanZone
Chaos2DBombAutoZone
Chaos2DMoveGravityTestZone
Chaos2DTogeZone
ChaosManHoleWanwanZone
ChaosManHoleZone
CoconutsGravityZone
CoinInfernoPlanetZone
CommonTshapeZone
ConfirmObj
CosmicBirdRoad
CylinderExplainTest
DarkRainbowCubeZone
DarkRiverBombZone
DarkRiverCylinderLiftZone
DarkRiverDashZone
DarkRiverMoveTwinLiftsZone
DarkRiverSanpoZone
DarkRiverTamaKoroZone
DarkRoadTest02PlanetZone
DimensionVrTest01PlanetZone
DrillPlanetMazeZone
DrillUpDownPlanetZone

E3MovAppearFleetZone
E3MovBigSmall
E3MovCloud2DPlanetZone
E3MovCloudGardenGalaxy
E3MovCloudSliderPlanetZone
E3MovCreekPlanetZone
E3MovCutTimberPlanetZone
E3MovDashYoshiZone
E3MovDigMineBossZone
E3MovDigMineInsideZone
E3MovDigMineStartZone
E3MovDrumCloudPlanetZone
E3MovFlowerBeeTutorial00Zone
E3MovFlowerGardenPlanetZone
E3MovFlowerHighlandGalaxy
E3MovFlowerJumpBallZone
E3MovFlowerPlantPole00Zone
E3MovFlowerSlider00Zone
E3MovFlowerWallJumpTutorial00Zone
E3MovHipDropMovePlanetZone
E3MovLightLabyrinthPlanetZone
E3MovMarioFacePlanetZone
E3MovMizutamaPlanetZone
E3MovMokuValleyEntPlanetDemoZone
E3MovMokuValleyEntPlanetZone
E3MovNailedUpHanaPlanetZone
E3MovOpeningCloudZone
E3MovPurpleCoinInfernoPlanetZone
E3MovRedBlueEx
E3MovSearchWanwan
E3MovSkyIslandBarrelPlanetZone
E3MovSkyIslandShipPlanetZone
E3MovSnowYukkinaZone
E3MovSnowZone
E3MovStartJourneyZone
E3MovTubeSliderTutorialGalaxy
E3MovYoshiPlanetZone
E3MovYoshiYCaptureZone
E3YoshiSpinDriver
EarthenPipeRoomA
EarthenPipeRoomDZone
EasyMoveBlockZone
EasyRedBlueBlockZone
FingerHeadTestZone
FireWoodBoxPlanetOrgZone
FLDZAKOPRD
FollowerDrillBossImageZone
GambleDiceTest01PlanetZone
GambleDiceTest02PlanetZone
GambleDiceTest03PlanetZone
GambleDiceTest04PlanetZone
GliderDangerCaveZone
GoharaTestA
GoroDashOrg01Zone
HashimotoTest23Map
HashimotoTest27Map
HashimotoTest42Map
HashimotoTestIZone
HayakawaBossTestSimpleStage
HayakawaBossTestStage
HayakawaHeadingPanelEasyStage
HayakawaHeadingPanelHardStage
HayakawaHeadingPanelSuperStage
HayakawaHeadingPanelUltraStage
HayakawaRideTestStage
HayakawaTestStage
HayashidaSwimTest
HayashidaTest
HoleSphere2Zone
HoleSphereZone
HoneyBeeSmallVillageTest01Zone
HoneyBeeVillageHomeZone
IslandFleetNewGavityZone
KarakuriWanwanTest
KingTossinTestZone
KoopaBossLv1Zone
KoopaVs1RoadDossun01Zone
KyarKyarOutBreak
LargeActionPlanetAZone
LargeActionPlanetZone
LavaFluffZone
LavaRelayPlanetZone
LavaSwimPlanetZone
LeafBoardCoinPlanetZone
MagicBlueStarZone
MagicDarkMatterDrillZone
MagicDarkMatterGCapZone
MagicLeafZone
Mario64Battan
MarioFacePlanetYokobe
MarioFaceShipNewTest03Zone
MarioFaceShipNewZone
MarioFaceShipTest02Zone
MessageCheck
MinetaStageObjTest
MoguchiRestartZone
MotokuraSnowAZone
MotokuraTest2DEnemy
MotokuraTest2DSwim
MotokuraTest2DSwim2
MotokuraTest2DSwimMap
MotokuraTest2DSwimTutorial
MotokuraTestBalloonYoshi
MotokuraTestFly
MotokuraTestJrLv2Boss
MotokuraTestMapObject
MotokuraTestNewCastle
MotokuraTestNigero
MotokuraTestPlanetShip
MotokuraTestSnowObject
MotokuraTestSwim
MotokuraTropicalPurple
MtEnemyPark01PlanetZone
MtEnemyPark02PlanetZone
MtEnemyPark03PlanetZone
MuimuiPlanetZone
MurataTest
MysteryCandyTest01PlanetZone
NigeroLv2Test01PlanetZone
NigeroLv2Test02PlanetZone
NigeroPlanetZone
OmoteuLandManholeLift1014Zone
OtaTestGalaxy
PeachCastle2DMario1Zone 
PeachCastle2DTest03Zone
PeachCastle2DTicoMeetsTest02Zone
PeachCastle3DZone
PeachCastleFinalStartZone
PeachCastleInsideZone
PeachCastleTown3DOrgZone
PenginAquariumZone
PetoTest
PettanWalkPlanetZone
QuicksandDarumaSamboZone
QuickSandFireTestZone
RainbowRoadA
RedBlueEx
RockBowlingLv1Test1PlanetZone
RollingRockBowling
RotatePurpleCoin
RotateWoodChallengeTest01Zone
RotateWoodChallengeTest02Zone
SearchWanwanTest01PlanetZone
SeesawCylinderTestZone
SeesawMoonTest03PlanetZone
SeesawMoonTest04PlanetZone
SequenceBeforeKoopaZone
SequenceNormalEndZone
SequenceStar120Zone
SmallPlanetBridgeZone
SmallRedBlueClimbZone
SpinClimbTowerZone
SpinGravityChange2Test
SpinGravityChangeTest
SpinGravityChangeZone
StarCreekTshapeZone
StorybookDemoTest01Zone
StorybookDemoTest02Zone
StorybookTestGalaxy
StrangeWaterPlanetZone
SugawaraTest
Sumaki2DTest
SumakiEnemyTest
SumakiFlowerTest
SumakiNPCTest
SumakiSphereTest
SumakiTest
SumakiWaterTest
SurvivalGrapyon02Zone
SurvivalKaronCubeZone
SurvivalPetariZone
SurvivalPukupukuZone
SurvivalWanwanZone
SwitchMoveBlockTest
SwitchMoveBlockTest2
TakeuchiNpcTestZone
TakeuchiObjTestZone
TakeuchiTestGalaxy
TakezawaTestA
TakezawaTestAGalaxy
TanakaTest
TimerSwitchingPlatformTest2Zone
TogezoTutorialZone
TwoSidesMazeZone
VSBossMenbosaPlanetZone
VsKokoopaShipLv1Zone
VsOtaRockTankLv1Zone
WanwanSw01PlanetZone
WanwanSw02PlanetZone
WatanabeTestF
WatanabeTestH
WatanabeTestL
WatanabeTestO
WatanabeTestS
WatanabeTestT
WatanabeTestV
WhiteSnowBlockTest01Zone
YamaguchiTest01Zone
YamaguchiTest02Zone
YamaguchiTestItemDrill
YokobeRestZoneA
YokobeUsefulMapPartsStageA
YokotaSurfingPurpleCoinStage
YoshidaTestHammerBros
YoshidaTestHammerBrosSecond
YoshidaTestHammerBrosThird
YoshidaTestKoopa
YosshiFacePlanetZone

…and here are the empty galaxies:

GemAsteroidGalaxy
HomeCenterTest01Galaxy
KoopaCastleGalaxy
KoopaVs1Galaxy
MarioFaceGalaxy
RedBlueExTest01Galaxy
SurvivalCosmosGalaxy
TemplateGalaxy
YamaguchiTestGalaxy
ZakoParadeGalaxy

Obviously, most of these are test stages or are from the E3 Demo, but there are many that hint at completely removed stages!