Your question has several aspects that are more subtle than first apparent when you pose a question like that.
Special Education (as opposed to regular education) teachers have specific training requirements under IDEA. You can find a summary of this information here:
http://www.wrightslaw.com/idea/tchr.hq.require.htm
These requirements focus on academic qualifications - does the teacher who's teaching math have a certificate to teach math? The question of whether the teacher has been trained to teach students with a variety of disabilities is not really addressed as far as I can find. IDEA requires that a teacher hold State certification as a Special Education teacher. What that means varies from state to state and is governed by State regulation.
But teacher training is not the key issue when you are talking about FAPE.
Rather the test is whether the child is receiving the instruction/services required by the IEP so that he/she is receiving FAPE.
FAPE is not measured by the qualifications of the teacher or their training in specific areas of disability. This has been established through case law and there is no basis under IDEA for a due process claim simply because a teacher is not qualified or doesn't have specific training.
If a teacher does not meet the requirements of either IDEA or NCLB then a procedural complaint can be filed against the LEA. But it does not affect FAPE.
Results are what count.
IEP's can call for either general ed or Special Education teacher training but rarely do so.
Reading is a classic example - most Special Education teacher training programs do not include specific instruction in teaching reading to children with reading disabilities. Really. So an IEP for a child with reading disabilities probably should specify the teacher's training and what method the teacher will use to teach reading. There is ample evidence that support the use of specific reading interventions/programs for children with reading disabilities and naming the program the IEP team agrees is appropriate is a very good idea. Eclectic instruction has been shown to be much less effective compared to using a standardized intervention program.
Patricia