2nd grader with 504 for ADHD not getting support he needs

I feel your pain. You just have to stay in constant contact with the school. Ask for an SST meeting at the beginning of every school year to get the new teacher on board with techniques that work. Stay on them. Ask for a weekly email from the teacher about how things are going. Involve your school's principal and guidance counsellor.

In my opinion, you should only be looking forward and trying to figure what needs to happen to help your son succeed in school. Forget about what has already happened. Who cares about the bad behavior grades of a small child? If it will impact your ability to get him into a fancy private school that school probably wouldn't be a good fit for him anyway. Understand that the school didn't give him ADHD and he's probably very challenging to have in class (my son is). Just focus on what you can do to make sure that he doesn't hate school. My son is allowed to move around the classroom when he needs to as long as he doesn't bother the other students. If he wants to stand to do his work that's fine. We have a lot of different agreements like that with the teacher. Believe me, if you can figure out an accommodation that will work, the teacher will do it because her life will be easier. 

Treat the school like your ally in this instead of the enemy. I've found that sitting down with them, acknowledging how difficult my son is to have in class, asking them for suggestions for things that I could be doing at home to help them, have really worked for us. My husband approached the school with anger that they weren't doing what they were supposed to do and it took me a long time to repair the damage that he did. 

Hello, Totmom.  I had a similar situation with my son in first grade.  I didn't have funds for a lawyer, but I did use vacation and FMLA time (you are eligible because your son has a medical condition) to take time off work and visit his class room - a lot.  I called lots of conferences with the teacher and the principal if there were reports of bad behavior.  I asked "what are you going to do to fix/change/stop this?" a lot.  In other words, I was all over the unprofessional teacher like white on rice.  It got so acrimonious she was inviting her union steward to the meetings.  I didn't give a flying rat's ass, frankly, her poor teaching skills and job performance were the whole reason we were there.  Every time we met, I got the 504 updated and signed with what ever they said they'd do to fix the bad behavior, then I followed up at the next meeting.  Example:  "So you said you'd separate my child and bully, but they're in math group together.  Why is that?  Isn't that a violation of the 504?"  Because I was in their face so much, the bad behavior declined.  Downside:  The other parents in my child's class treated us both like pariahs.  Upside:  Ineffective teacher was gone a year later so at least she couldn't treat someone else's child so poorly.  What this experience taught me is that you are your child's best advocate at school.  As you have experienced, you will get the civil servant shrug unless you push, push and push.  My child is in eighth grade now and I still have at 504 meeting at the beginning of the year, one mid year and a month-before-school-ends check in.  I've also escalated up to principals or other administrators immediately if I felt the teacher was blowing me off.  Am I everybody's favorite PTA mom?  Heck no.  Is my son getting the education and accomodations he needs?  Heck yeah.  I'd rather be *that* mom with an educated kid than everybody's friend, I guess.  YMMV.

I wouldn't worry about grades for a second grader.  When they get older it's more important.  Try to be nice about it.  If there is a bully, consider writing an email to the teacher with a copy to the principal and say something like:  "Thank you so much for placing him in this other class, he seems to doing much better, but he has told me about a kid in the class that is bothering him.  His name is X.  Not sure how to handle this, perhaps you guys can check in to this."

You obviously have checked with a therapist and determined he has ADHD and maybe he is on medication now or not.  The therapist should be your guide.  When you have a meeting for your 504, bring the therapist along too.

Good luck.