Jacqueline, despite being five foot four at most, quickly became an unpopular target when several larger wrestlers, men included, found she could easily toss those much larger than herself.
Rey Mysterio Jr. A tiny little guy with big Puppy-Dog Eyes who would look like a kid playing superhero in his backyard, almost across the border into Moe...except he's held as many or more titles than any giant in the ring twice his size and can usually be found, especially recently, whomping the hell out of those same giants.
Bryan Danielson's role in the swarm, where he would seem lost, trying to keep a straight face in the face of Paul London's inanity. Also, his re branding into "Daniel Bryan", who Bella Twins "competed" over, assuming he must be virgin. All the same, Danielson was never lost or underestimated once he was in the ring and the bell rang. He nearly caused the breakup over Team Hell No over getting the idea someone thought he might be the weak link of the team, even though everyone but Jerk AssSeth Rollins told him it was not the case.
Since there was no women's championship for a stretch of The Attitude Era women for the first time in a long time found themselves liable to compete with men in the WWF. Chyna quickly disproved that this may have been problematic by repeatedly beating up Bret Hart and winning the intercontinental championship from Jeff Jarrett and feuding with Chris Jericho.
People are prone to worrying about Daizee Haze on the account she really isn't that big, a fact she knowingly took advantage of in Chikara, screaming and cowering before anyone who might try to attack her, and then beating them relentlessly if they should flinch. Hardly anyone in NWA Wildside condoned Sal Rinauro's harassment of her, but after seeing her wrestle, no one was especially worried, as Haze demonstrated she could take care of herself.