Quick summary of how I imagine how story going because I had to much time to think about it:

The onceler, Lorax and some of the animals fell into a magical portal in the forest leading them to candy land. This happens after Onceler gives up on the thneed but still has hope on starting some kind of business.

After the wend up in candy land and they get to know the people there, Mr Mint and Onceler get along very well because of their carefree attitude. Eventually getting the business idea to use the extra peppermints to sell in the real world- then it expands to sugar pulms, lollipops, gumdrops, ice cream and more. From a little shop to a Willy Wonka factory to a amusement park, HE DOESN'T STOP. (ironically I imagine lord licorice benefits from this because the unrest in the land lets him take the throne without any objections)

Same environment story but basically when a company takes resources, makes resorts and causes political instability in other countries.

I really didn't need to do all of this

I imagine Mr. Mint in the story has agency in the whole thing but didn't use it until it was too late. My imagining of Mint is that he was related to the royal candy family and had the role of the main man of the royal guard but left because it was too much responsibility and rather live more freely. So instead became the royal rangers of the peppermint forest, which wasn't that hard for him, he got alone time to make music and play with the peppermint beavers. Peppermint did grow fast like a weed and can easily invade other areas if he aint chopping them down. So when Onceler came along and they gotten close, of course he will give his bud some peppermint, they have MORE than enough! And when he kept asking for more and more even though it's starting to hurt the beavers dam he still helped.

Eventually he started to see the situation for what it is but by then almost all the candies were gone.