UPDATE!: As of the release of the Wave 5 of the Mario Kart 8 Deluxe Booster Pass, my Pipe Frame Theory is partially debunked. Wiggler, Kamek, and Petey Pirahna's Pipe Frames all use colors used by previous drivers (in each respective character's Pipe Frame's case, Orange, Sky Blue, and Green).

While this doesn't fully debunk my theory, it does put a splash of cold water on it. Ultimately, we can only wait until Wave 6 of the Mario Kart 8 Deluxe Booster Course Pass to see if the upcoming 2 characters for said Wave will have Pipe Frames with color schemes that are unique from everyone else's.

Original: I have been thinking about this theory on upcoming characters for a while now ever since Birdo was added into Mario Kart 8 Deluxe via Wave 4 of the Booster Course Pass.

This theory around upcoming Mario Kart 8 Deluxe characters revolves around the "Pipe Frame" kart & all the colors it has for the characters in the roster (both current and upcoming).

I call it the "Pipe Frame Theory".

What is the "Pipe Frame Theory", you may ask? Well, it goes like this...

You see, as we all know, some karts have different color schemes / paint jobs that correspond with a specific character.

The standard vehicles kart, bike, and ATV) and the Pipe Frame are the most significant of this trait as they all have the largest variety of paint jobs corresponding with all the characters in the roster.

There are a few exceptions.

When it comes to the standard vehicles, some characters share the same vehicle color scheme, such as Mario and Baby Mario sharing the same paint scheme for their standard vehicles.

Daisy & Baby Daisy are a strange exception to that trait for their standard vehicles, as the multiple colors of their ATVs are somewhat different rather than beinf the same colors.

But the trait of shared vehicle colors between multiple characters is more significant with the Pipe Frame, as characters like Rosalina, Lakitu, and Baby Rosalina, for example, use the same color of Pipe Frame; in the aforementioned characters' case, their Pipe Frames are all Sky-Blue (which is strange considering that Rosalina's Pipe Frame is colored Turquoise / Cyan / Teal in Mario Kart 7 and in Mario Kart Tour).

But the Pipe Frames & their corresponding characters that I'm going to be focusing on to explain the "Pipe Frame Theory" to theorize on Upcoming Characters for Mario Kart 8 Deluxe are Birdo and the Koopalings (Larry Koopa, Iggy Koopa, Lemmy Koopa, Roy Koopa, Wendy O. Koopa, Morton Koopa Jr., and Ludwig Von Koopa).

You see, when Birdo was updated into Mario Kart 8 Deluxe, Birdo's Pipe Frame was unique from all the other characters' Pipe Frames.

The primary color for Birdo's Pipe Frame is Hot Pink, just like Wendy O. Koopa.

HOWEVER, rather than its engine components, exhaust pipe, and kart joints being multiple colors like with Wendy O. Koopa and the Koopalings' Pipe Frames, the colors of the engine components, exhaust pipe, and kart joins of Birdo's Pipe Frame are the same as everyone else's Pipe Frames - gray engine components, a gold / dark yellow exhaust pipe, and gray and white kart body joints.

You can see what Birdo's Pipe Frame looks like in this picture I took, as there has yet to be any screenshots and/or sprite/model extractions of Birdo's Pipe Frame to be uploaded on the Internet by anyone.

With all that detailed, this led me to theorize that the Pipe Frames for upcoming characters like Petey Pirahna, Wiggler, and Kamek will have paint jobs / color schemes unique to them and no on else.

For instance, Kamek's Pipe Frame could end up having a turquoise / cyan / teal paint scheme like Lemmy's Pipe Frame, but Kamek's Pipe Frame would have the standard colors for the engine components, exhaust pipe, and joints.

This has also led me to use that knowledge to come up with possible theories to what characters could come based on what colors their Pipe Frames could possibly have.

For example, if there would be a Magenta Pipe Frame like Roy's Pipe Frame, but that Magenta Pipe Frame would have gray engine components, a gold / dark yellow exhaust pipe, and gray & white joints like the Pipe Frames used by everyone other than Roy and Koopalings, that Magenta Pipe Frame could possibly be for...

Pauline, the 1up Girl and mayor of New Donk City (or mayor of New York City in The Super Mario Bros. Movie)

In fact, Pauline DID drive a Magenta Pipe Frame in Mario Kart Tour, so she could most definitely do it again in Mario Kart 8 Deluxe.

Needless to say, with Birdo being the only character with a Pipe Frame unique from anyone else's, and with 3 confirmed upcoming characters yet to be updated into Mario Kart 8 Deluxe (Petey, Wiggler, and Kamek), I would like to gather more details to put into my "Pipe Frame Theory".

In other words, once Kamek, Wiggler, and Petey Pirahna get updated into Mario Kart 8 Deluxe via Wave 5 of the Booster Course Pass, AND I see what their Pipe Frames look like, I might have a better understanding & more details for my "Pipe Frame Theory".

But as with any other upcoming thing, we ultimately have to wait and see what happens.

I do hope Pauline will be one of the 2 remaining characters coming to Wave 6 of the Booster Course Pass. And if she will, then that all but confirms my "Pipe Frame Theory" and how Pauline will once again drive a Magenta Pipe Frame, just like in Mario Kart Tour (except that in Mario Kart 8 Deluxe, the Magenta Pipe Frame's color scheme / paint job, especially with the colors for the engine components, exhaust pipe, and kart joints, would be unique to Pauline, of course).