Proving that not even Square is devoid of marketing gimmicks, for Chrono Trigger the famous comic-book artist Akira Toriyama was hired to do the character designs. This was by no means a small detail, since Mr. Toriyama is one of the biggest names in Japanese comic-books, having penned both Dr. Slump and the mega-blockbuster DragonBall series in addition to being one of the two only comic-book artists (the other being Osamu Tezuka) whose work has been shown on classical Japanese museums (not cel-galleries and stuff like that). Eventually others would use Toriyama's work to sell videogames (ie. the Tobal series).
While the information about Toriyama is notable, I'd hardly say that getting a known and skilled artist constitutes a "marketing gimmick". There's also that this was far from the first video game he'd worked on. Ignoring games based on his works from other media, he was always one of the key members of the Dragon Quest team, one of the biggest series in Japan for nearly a full decade prior to Chrono Trigger's release.
He wasn't even the only Dragon Quest guy to have a role in the title--there's also Yuji Horii. It's the combination of known big talent from competitors Square and Enix that has even the game referring to it as a Dream Team in one of the goofier endings.