Some TMNT stuff really isn't for little kids.
In the IDW continuity, Stump is a tree-like alien and the owner of the Intergalactic Wrestling Federation. He was also a real estate developer who once made a business deal with General Krang to clear-cut all the other trees on his homeworld (an act of genocide) for profit. Nevertheless, believing Stump could testify against him in The Trial of Krang, Krang sent Hakk-R to silence him, which led the Neutrinos to seek out, defend and recruit Stump as a trial witness.
Stump first appears in-person in Teenage Mutant Ninja Turtles: Dimension X issue #3, when the Turtles came to meet him at his home and primary place of business, Stump Asteroid, where Stump and Sling's Intergalactic Wrestling Federation is headquartered. When initially questioned, Stump casually revealed that he actually sold the "lumber rights" for his entire homeworld to Krang, an unsavory admission that provoked Raphael into questioning Stump's value as a witness in the first place. Nevertheless, with Stump's life in danger, the Turtles kept insisting he come with them to Planet Neutrino for the trial, but Stump insisted he remain for the rest of a scheduled wrestling event, Grappleganza. Stump agreed to leave if the turtles participate in live-televised wrestling matches. Hakk-R showed up during the matches, but even then, Stump was more concerned with continuing the profitable event.
In The Trial of Krang, part 2, Stump was one of several witnesses to testify in court against Krang in front of presiding Judge Gorath. But Stump's testimony went terribly wrong—on Fugitoid's questioning, Stump not only readily volunteered that he sold the other tree people on his homeworld to Krang to be slaughtered for lumber, but expressed regret that he didn't make more profit out of it than he could have. Krang was delighted at how much Stump had undermined the prosecution's case against him, and Krang's attorney Vin-Bini decided not to even bother cross-examining the witness. Later, before all the remaining witnesses could finish testifying, the trial was abruptly adjourned when Maligna launched an assault on Planet Neutrino.
In The Trial of Krang, part 3, during the Malignoid attack, Stump was cajoled into one desperate move to save the lives of himself and everyone else on Planet Neutrino—he bribed Hakk-R an enormous sum to defect from Krang's service and help defeat the Malignoids. The unsavory deal spared Hakk-R from prosecution for his many extrajudicial murders (including the killing of Judge Gorath in his own chambers), but it was tolerated as a necessary compromise that helped save the Neutrinos from annihilation. Though Stump had indeed proven himself a complete liability during the trial itself, Krang would eventually be convicted anyway with the help of the other witnesses' testimonies, especially that of Leatherhead.
- Like the Archie TMNT version he is based on, Stump is a parody of Donald Trump. But whereas the Archie versions of Stump and Sling were a parody of Trump and Don King as 1980s pop culture personalities, the IDW version of Stump takes a darker turn, parodying Trump's reputation as a corrupt and greedy real estate developer, as an alleged colluder with hostile foreign powers, and as an unfiltered mouth whose comments have a tendency of undercutting his partners and allies.