Mikayla is a giantess, but her height is currently unknown. She uses her height to her advantage as she goes around, collecting people for her collection of tiny people. It has been strongly implied that she has collected Vanessa, but no physical evidence of this exists.
Mikayla is a cruel woman who cares for nobody but herself and Aurora, her robotic servent and closest friend. She will do anything to get what she wants, even if it means killing millions of people just to collect one or two people that she wants in her collection. There is no kernal of goodness inside her, as she had been bought up to believe that anything smaller than her does not deserve her respect. Instead, she enslaves some of her collection to worship her and to do what she demands of them so that she can maintain her air of superiority.
Mikayla and Tetre are longtime enemies of each other, having encountered each other several times over the last century or two. Because of Tetre's powers and that she is immortal, Mikayla considers Tetre to be the most important missing element of her collection. The two were originally friends, but when Mikayla was indoctrinated in the ways of giantess superiority, she turned against Tetre and has been hunting her ever since.
Mikayla first appears in The Visit, where she attacks Flamber and Sheebop's house after Tetre's debut appearance. She gave forwarning to Tetre to evacuate the house so that she can take her and Dodeca as part of her growing collection. However, this backfired when Paige forcibly evacuated the house of everyone but her. Mikayla then spoke face to face with Paige before swatting the Gardevoir down with a single finger.
She later appeared in another RP where she sent a robot called Aurora to kidnap Teddy. This plan worked successfully, but Paige was also taken by Aurora. Only then was the true extent of Mikayla's collection revealed and she was seen to have thousands of glass jars containing many living humans and pokemon. Mikayla mentioned here that Vanessa is in her collection, but she wasn't believed.