Pokemon battles are alone among the major sports in not considering tripping to be any sort of rules infraction, as befits the varied, anything-goes nature of these competitions. This is not, however, to say that a trip is a crowd-pleaser; it is always more exciting to watch a competitor land a big hit than to watch them stumble and fall into goo.
Hisuian Goodra were long considered the most laughable of the fully-evolved dragons, silly creatures who never matched the menace of their fiercer, faster counterparts; unfortunately, this is also how they are most often remembered. Historical archives of the Sinnoh League suggest otherwise. Land-based pokemon could not help but get stuck in their goo or tripped by their thrashing antennae, leaving them a stationary target for a gigantic rolling creature which must have been far more terrifying than any Miltank or Donphan. Trainers of this era did not take Goodra lightly.
Which makes it all the more puzzling why Hisuian Goodra are so rarely seen today, in high-level competition or anywhere else. The pokemon it countered, such as Garchomp, are if anything more popular now than in colonial times. While many casual fans and low-level trainers found Goodra's fighting style unappealing, professionals have always appreciated whatever worked; misconceptions about any species of pokemon can only last until one loses to them. Perhaps it is simply that Goomy was always a rare pokemon, and climate-controlled pokeballs and indoor temperatures rarely lead domestic ones down the path necessary to create a Hisuian Sliggoo, let alone a Goodra. The so-called "Kalosian" Goodra, although far less popular than the Hisuian at its peak, continues to regularly obtain league placements.
But trainers are always on the lookout for a surprise strategy, so I suspect that Hisuian Goodra has not yet won its last championship.