Oh I experience the wall jump (glitch) but as Mini Mario in world 7-A in NSMB, the pipe leading to the goal; I entered a horizontal green pipe while in midair. Also I did it again when real wall jumping to get the last star coin in w4 ghost house (near the secret exit) (just to let you know when wall jumping as a glitch, you'll notice that mini Mario does a "normal jump" (and normal jump sfx) and not be forced away from the wall). On a real ds system (happens rarely though).
I also found another glitch related to that: after real wall jumping, if you don't press left or right (so you keep your velocity) and hit the opposite wall, the player may "catch" the wall, slowing down a bit, then stop for a frame without "wall-sliding" then go normal.
In smw: Also about the layer 2 with the player y speed, if you stand on a layer 2 platform on the edge, and then walk off the edge, you fall faster than walking off the platform layer 1 edge. You don't need L2 water tiles to do that. Because of this, I just noticed that if you place a 1-block wide gap between two L2 platforms and try to gap-dash across it, it's impossible to
not fall in between, even at max running speed.
Nintendo programmed it like that so Mario's y-speed is slightly higher when standing still on L2 (look on the debugger showing the current y-speed of the player's (the player is standing on he platform, and his y-speed is greater than #$06 when not holding the jump button)), this is so that when the platform descend, Mario will "stick" to it and not "fly off of it" (since before his gradational acceleration is he slowest velocity than L2 at this point).
Also, just to let you know, the patch for the on/off L2 fix is still waiting to be moderated, so if it got rejected for some reason, your link for that gets broken. I'll let you know of that happens.
Edit: I found another glitch, if a Magikoopa's Magic spell or a Bullet Bill goes past the bottom of the screen in a horizontal level (by scrolling the screen upwards), they disappear. This makes it impossible to design levels where you fall and encounter these sprites, by making them appear from the bottom of the screen (they try to spawn by entering the screen, but the game immediately assumes they are leaving the screen and erases them) .
And another glitch with the magikoopa's arm holding the magic rod, if they go past the top or bottom of the screen's edge, it will "wrap", similar to extended sprites like the puff of smoke or the bonus game sprite (if you enable scrolling) (not that these two will work on all edges of the screen, magikoopa's arm is only top/bottom.)
Man, there a lot of of glitches in smw, well at least it's not as bad as Pokemon red/blue (oh gawd, look up in
bulbapedia in the criticisms, it has
WAY more exploitable glitches in these games)
(Speaking of a null/invalid sprite in yoshi' mouth, it kinda reminds me of the extremely dangerous glitch castle crush form dkc2dkq, where you are holding a glitchy sprite and that releasing it can crash the game).
Give thanks to RPG hacker for working on Asar.