SAT or ACT is achievement and prepping is OK. Old SAT is quasi IQ test but new SAT format is not.

IQ tests like WISC should not be prepped.

Prepping will most likely improve the score and many schools are prepping their students to improve their standing. 9th grade is way too early for the school to do it. Probably the administrator is super ambitious!

7th or 8th grads is good to take the test. It won't stay in the record and the kid will have experience taking the test.