This page explains in detail the interactions between the Mario series and the Transformers series.
The April Foools image from Derrick Wyatt's blog. Huffer and Pipes are in the middle.
On April Fools Day 2009 Derrick Wyatt, art director and lead character designer for Transformers Animated posted on his blog an image of various transformers characters redesigned in the cartoon's style, stating that they may or may not appear in the show. These included Huffer, a truck Autobot originally from Generation 1, and Pipes, a retool of Huffer. Here they're redesigned to look like mustached workers in overalls, with Huffer being shorter and wearing an orange shirt, while Pipes is taller and wears a blue shirt, therefore looking very much like the Mario brothers. Of the two only Huffer made an actual appearance in the show, while Pipes only appeared in comics:
Transformers Animated episode Decepticon Air[]
May 2, 2009
Huffer's cameo.
Mario
Transformers
In the tenth episode of season 3 (Epiosde #39), Huffer debuts in a crowd scene welcoming home Sentinel "Magnus" and cheering on the capture of several Decepticon prisoners.
He was later seen among the group of Autobots that Captain Fanzone Transwarped into in the following episode, "This Is Why I Hate Machines".
Transformers Timelines: Moving Violations[]
March 9, 2011
Mario
Transformers
In this Club story that serves as an introdction to the comic "The Stunti-Con Job", Huffer and Pipes make a background appearance in the first panel.
They also make a cameo appearance in "The Stunti-Con Job".
License[]
The creators of Transformers Animated and Transformers Timelines didn't hold any right over Nintendo's Mario, but they only included subtle references to the characters.