I’d comment on the fact that being a science intern rather than, say, a law student or poli sci major is a poor route to wealth and power, but this is a superhero setting. Anyone with the least bit genre awareness interns at a lab solely in the hopes of gaining superpowers at random. It’s probably mentioned right there on the standard hiring forms these days.
“Following recent class action suits, we are legally required to inform you that working at UNethiCo Labs does not guarantee you will gain metahuman abilities during your employment, and we cannot be held responsible if you fail to do so. Also, please keep in mind that deliberate self-irradiation or willful consumption of bio-reactive substances are firing offenses as well as voiding your health insurance policy.”
Both builds look quite solid, with strong A/A pairings that play very differently. Failing to foil her first form could easily lead to having a rematch with her second later on.
I had a somewhat similar villain who temporarily overwrote your mind with a copy of his own using Suggestion, with the added flavor of being able to create psychosomatic physical changes in people who were subjected to the effect long term or taken out of action. He used the same Brainwashing Zone upgrade you’ve got here, unsurprisingly - it’s good for that sort of transform.
One of my former GMs did the “polymorpher” trope with a djinn-like villain and gave him a hallmark power called Metamorphosis that was essentially Shapeshifting but only on other living beings. He also had Transmutation and actual Shapeshifting, so by the time he was done nothing and no one was left the way it started. Mechanically it was all still tied to his abilities, although he also did a fair few Overcomes (usually Risky for added effects, sacrificing minions to pay the twist) for annoying improv effects.
I think I liked his approach best, but I’m not sure it’d work so well for a PC hero. Bit strong to alter others’ forms regularly, and using it creatively with Overcomes requires a lot of GM oversight that a villain doesn’t need so much.
Also, I am embarrassed to admit I knew the name Beijerinck from the lunar crater named after him, but had no idea who it was named for until today. One of our old scifi RPG one-shots had the PCs exploring the Gagarin plain looking for a crashed ship, and the crater was up at the edge of our search zone.