Mario galaxy 1 & 2 glitches iceberg
"Every" Glitch in Super mario galaxy and Super mario galaxy 2. This is not really an extensive list, i might've forgotten a couple of glitches, or left out some of them because they were too repetitive or uninteresting. Also note that some tier placements might not be fully accurate, it's just very difficult to judge how unknown bugs are, so some entries might belong one tier up or down according to you, but i tried my best to make this iceberg as accurate as possible. Also also, the entries aren't necessarily in order, just because one is at the top of a tier doesn't mean it's less obscure then one at the bottom of the same tier.

The tip of the iceberg
Very well known, more general glitches
Slope glitchGenMvmt
Momentum conservationGenMtm
Infinite fluttersGenImg
Backwards momentumGenMtm
Exiting gravity fieldsGen
The surface
Pretty famous bugs
Starshroom clipClp
Flipswap momentum glitchMtm
Bringing Yoshi to final bowser
Extended yoshi tongueVis
Yoshi crouching glitch
Yoshi bloated cheeksVis
Freezeflame oobOob
Oob in dreadnoughtOob
Dice room skyboxVis
Cloud camera clipVisImg
The shallow waters
Still somewhat known exploits
Lil cinder visual glitchVis
Clipping inside the dusty dune wheelsClp
Deep dark oobOob
Swimming with bee mario
Smeech in "got a star"Vis
Fluttering sidewaysGenMtm
Death in the credits
Stopping meteoritesVis
Lava boostsGenMtm
Cloud boostingMtmMvmt
Fast swimmingMvmt
Final Bowser cutscene skipVisSftLck
Void in melty monsterVisImg
Fearsome fleet teleportation
Freezy flake goomba statueSftLck
Lillypad raising
Supermassive piranha plantVis
1st person creditsVis
Walking in water with yoshi
The depths
Your average smg fan knows less than half of these
Deep dark parasol glitch
Early volcano activation
King whomp flingMtm
Stuck crabVis
Throwback 2 teleporter island
Crystal floatMvmt
Slope boostingMtm
90 degree wall jumpMvmt
Backwards long jumpsVisMvmt
Cheating death/gameover with a coin/1up
Double wall jumpMvmt
Luma bounce/Npc bounceMtm
Invisible platform in sweet mystery
Under the ghostly mansionOob
Upside down lumaVisImg
Slope glitch with bee mario
Swimming in loopdeswoop
Talking to toad on the slingpod
Megaleg cutscene skip
Weird crushing deaths
Yellow flash in slipsandVis
The deep waters
Only speedrunners and really passionnate fans are aware of these
Whomp clipOobClp
Empty planets of yoshi star
Shore launch/Penguin launchMtmMvmt
Ground pound switch exploitMtm
Mega sideflipMvmt
Top shelf softlockSftLck
ITC/BTC
Nemi boostMtm
Palm tree glitchMtm
Bunny changing directions
Yoshi in the slideSftLck
Boosted tripleMtmMvmt
Deactivated hammer broImg
Honeycomb superflightMtmMvmt
Fire flower spammingMvmt
Infinite rock jumpsMvmt
Triple jump preservationMvmt
Frame perfect ground poundMvmt
Dash pepper boosting
Camera cancelMvmt
Jump cancelMvmt
Boosted sideflipsMtm
Accessing the space junk launch star earlyClp
The abyss
Extremely unknown glitches
Invisible platforms in Ghostly SVis
Drip drop oobOob
Space junk 2 gravity field
Smeech wall clipClp
Galaxy 2 prologue skipClp
Invisible platform in honeybloomVis
Supermassive oobOobMtm
Dying while/after grabbing a starVis
Ground pound jumpsMvmt
Smeech getting smallerVis
Sky station oobOobMvmt
Throwback 1 corner clipOobClp
Tox box flingingMtmTasImg
Reachable purple podMvmt
Sweet sweet oobOob
Invisible platform in puzzle plankVis
Good egg 2 oobOob
Sky station softlockClpSftLck
Starshine beach oobOobClp
Bigmouth oobOob
Wrong low-poly
Clockwork clipOobClp
The void
Even the most avid glitch-hunters might not know all these bugs
Buoy base sling star landing momentumMtm
Melty monster lava boostMtm
Flipped swaphoppersVis
Throwback thwomp clipOobClpTasImg
Insurmountable ledge in cosmic coveVis
The ocean floor
Unbelievably strange and obscure stuff
Metal WSftLck
Cloudy court teleporter island