I'm not so much concerned over who's stronger than who, as much as I am her character being able to escape every single situation handed to her without any help, since she has about 1,000 useful skills. Also, I just find it a little silly for someone to have SO much, even if they are long-lived. Look at Wolverine or Ra's al Ghul; both long lived, neither one of them have THAT many skills. Both of them are also very smart and skilled in martial combat and tactics, but they're not ALSO super hackers trained in demolitions and espionage with shapeshifting abilities to boot, y'know? If we're going to play an Avengers-type squad I'd much rather see the characters with strengths that complement each others' weakness. If you're not planning on using the shifting much anyway, why not ditch it? As you said, we already have someone with animal mimicry anyway.