@jemarsiega
Hello! I am currently working in a montessori preschool/childcare centre in Australia. It would be advantageous for your wife to have the necessary specialised experience if she's planning to work in a montessori centre in Australia as well.
Anyway, yes, it's possible for her to apply as long as she has the qualifications for it. The first step is to take the IELTS (PTE and TOEFL are not accepted) with a score of at least 8.0 in Speaking and Listening and at least 7.0 in Reading and Writing. When she's done with that, the steps will generally be similar to other Visa 189/190 applications:
@lululucil
Hello! In your case, you should probably wait to get teaching units because the AITSL assessment will require you to have a teaching degree and teaching practicum. After that, you could proceed with taking the IELTS and the rest of the steps in applying for a visa. Otherwise, you might want to check if Psychologist is in the list of Skilled Occupations List so you can apply for that instead of teaching.