The Short Version: Head to Hazy Maze Cave, find the poisonous haze area, and break the block with the Mushroom. Next, go back to the two Monty Mole holes and run in a tight circle over the moles. It won’t be long before you start racking up several extra lives before the Mushroom wears off.
In a post of Super Paper Mario Wii Cheats one user, Overlord Goomba, posted a tip for making a lot of coins in a relatively short amount of time. The trick involves using a Catch Card SP to capture an Amazy Dayzee and then sell it at the card shop. Catch Card SPs usually cost 100 coins in the Flopside card shop and the Amazy Dayzee card can be sold in either card shop for 300 coins. This trick can be used to quickly max out one’s coins (and still have more cards in reserve).
Unfortunately, this trick requires access to level 5-2 and Flopside, so it’s not something that can be done early in the game.
Once you have at least one catch card (I’d recommend having two for the first trip) you’ll need to head to 5-2 and move through the star doors until you reach the door with the Yoshi statue. Just after the gap with the floating platform, but before the Yoshi statue, you’ll find an Amazy Dayzee in 3-D mode. As soon as you flip, just use the catch card.
I discovered an interesting cheat for Super Mario Bros 3 in Super Mario Bros All-Stars for Wii. Perhaps this is a bug or maybe even something that was by design. It may have existed in the SNES version though it’s been so long since I played it that I don’t remember. While running through World 1 I decided to save and see what happened when I reloaded the game.
When I reloaded the save I was disappointed to see that I would have to go through the levels again. But then I noticed that I had the same number of lives and the same items from before. I proceeded to play through World 1 and then stopped and saved before I got to the castle.
Using this trick I ended up with three warp whistles in World 1! I probably could have gained more but since I didn’t really plan to use them I instead started stocking up on items and lives. Using the old infinite lives trick on 1-2 it wasn’t long before I had several items and a good stock of lives before moving on to World 2.