Admitting that Triathlon is terrible is a little bit painful, considering how central he was to Busiek and Perez’s aforementioned run on Avengers, a nearly universally beloved comic run.
On the other hand, Triathlon is the Neapolitan ice cream of lameness. A former Olympic athlete make that “triathlete” Delroy Garrett found himself stripped of his accolades for cheating. Down on his luck and destitute, Garrett joined up with the Triune Understanding, a cult that was based around maximizing the physical, mental, and spiritual potential of human beings through the use of Thetan Rays or alien ghost masters or something.
As Triathlon, Garrett was able to match Captain America in terms of physicality. Really, his lameness stems more from the circumstances surrounding his joining the team, which was forced as part of a plot in which the Triune Understanding tried to infiltrate to the Avengers, using their powers of Affirmative Action and PR bullying to convince everyone but Iron Man that they really needed to hire more ethnically diverse Avengers, and why not Triathlon?
Poor Triathlon, you never stood a chance to be great.