Imagine a town filled with mini cranes that carry Chomps instead of wrecking balls and the cranes throw the Chomps like a boomerang much like the Electro-Koopas. While it has no Chomp, the cranes shoot Swoopin' Stus at you. You have to spray the crane so that when it gets the Chomp back, it accidently hits its roof with the Chomp. On another mission, the town is flooded in fire goop and you to use (American/Canadian) school buses to navigate through the goopy flood to a construction site and a secret stage. The school buses are semi sunk, with only their rooves above the surface. You can get inside a school bus by butt-stomping the emergency exit on the roof.

Nice. Anyway, I'm gonna make another level, but this won't be a main level (8 Shine Sprites), it'll be like one of those Delfino Plaza secret levels (1 Shine Sprite).

Shinemost Mountain: Mario lands in a small sandy-area that is completely fenced-in. In the middle of the area is a giant, tall vertical hill. Mario has to climb it to the top (like how he climbs one of those fence things from Ricco Harbor) and collect Red Coins and avoid falling enemies and obstacles. I got this idea from a video where somebody used a hack to let Mario climb walls.

Tanooki Highlands

This largely spread-out level takes place in the skies in the high tree-tops, where an entire civilization of Tanookis live and swing around the treetops. Yoshis are very common here.

I always had an idea of a snow mountain in SMS, but I never really thought deeply about it.

I got one!
- Inverno Mountain -
Name translates to Winter Mountain, as it is a mountain that retains its snowy features at all times. It is somewhat straightforward in design. Sliding is essential for quick travel down, with a lift to the side for easy travel up (many islands can be seen from the lift). Snowmen can be found all over the mountain, some containing Blue Coins, and one in particular hiding a pathway to the secret area (Snowmen can be melted with FLUDD or destroyed by ground-pounding them). Residents and Yoshis are somewhat uncommon.
EDIT: Came up with a mission where you have to roll a snowball down to the bottom of the mountain with many enemies on the way (and yes, it's just as fragile as the giant watermelon!). It gets larger the more it rolls, and it gets faster and harder to push up the larger it is. You can spray it with FLUDD to make it smaller, but spraying it too much will cause it to melt entirely.

Cool! (GET IT? HAR HAR!) Anyway, that level sounds awesome! I always wanted to expand on those icecubes you found in the secret levels and Delfino Airstrip, and that sounds like a great place to do it!

Maybe there could be a level where you traveled inside to the core of the mountain and there was a maze of those ice cubes and below was the freezing water that hurts you from SM64 and SMG. And maybe some of those Piranha Plant enemies that spawn from goop would be blocking some of the entrances so you NEED to spray water... UltimoPianta! Your level could have so much potential!

Meanwhile, I have another idea: A dry, dry valley that is completely empty and at the end of it is an ancient, abandoned pyramid and a few temples nearby. I'll get to work on it soon!

Why thank you. I actually had something much more simplistic in mind, but you expanded on it in a way I didn't think could happen.
Also, no offence, but that desert level idea sounds really boring. More boring than another desert level I know from another game. (Sonic & Knuckles's Sandopolis Zone)

No, it's fine.

Anyway, here's the level:

Scuro Valley (translates to Dark Valley)

A somewhat long level made of a dusty, dirty, and abandoned valley full of dead trees, Pokeys, and a few Stackin' Stus and some empty caves. Towards the end are three old pyramids, two almost completely destroyed and a third in the middle still standing. There is also a labyrinth of underground tunnels below, full of new scorpion-like enemies. Luckily, the tunnels provide excellent travel for going from one area to another. Also, to the far right, is an almost completely dried up river. To add to the theme, their is also occasional thunder and lightning, and the music is very low, so the player will mostly hear only the wind blowing.

Just wanted to create a creepy, intense level.

My next level will not take place on the island- but above it!

Nice. Definitely better than the way you described it earlier.
Also, your next level makes me extremely curious.

Awesome!

Got a new idea for a Custom Level!

We're doing a unit on tides and how the moon causes them, and I got inspired with this idea:

It takes place in a large, brick and concreted village in the middle of a large crater flooded water. There is a gimmick to this stage: the water constantly lowers and rises over time, like in SM64 Wet-Dry World, but this time it's automatic.

I'll give a title and a more detailed explanation soon.

Oh, and that other idea I had was a bust, sorry UltimoPianta.