transform, disguise oneself
ハウルならもっと派手なものに化けるわね
If it were Howl, he’d transform into something much flashier.
— ハウルの動く城 (2004)
だがこの本が大金に化けるはずだ
But this book could turn into a fortune.
— パディントン2 (2017)
年寄り犬に化けるなんて年寄りがどんなに大変なのかわかってるの?
Do you have any idea how hard it is to be old, disguising yourself as an old dog like that?
猫は化けると言われる。
It is said that cats can shape-shift.