So I was taking the AP Calc BC best and after we were done the person who sat next to me (my friend) said that he copied a lot of his answers off of me and then I told him that we had different forms which he was not aware of. What should I do? Will the college board waive our tests?? Will the school have to take the tests again?
You could convince him to cancel the test since s/he is well and truly screwed as the MC sections are scrambled. If your friend does not cancel the exam, his/her test will likely be flagged for irregularities due to the pattern of wrong answers. Additionally, if your school has an honor code, you should abide by whatever the code instructs you to do.
No
Thank you!! I’ll try and convince them. Also, what happens if your test score is flagged?
What is your school’s honor code?
If it requires you to reveal cheating when you know of it, then you have your answer.
If your school does not have an honor code, then it depends on your own.
Now for the practical answers:
Your friend (who hardly seems to deserve his name) will receive his own just deserts in the form of a lousy score [although who knows what match/mismatch there might be between your answers and what would be correct on his form and how good are you at Calculus anyway and so forth].
I doubt that the College Board can or would be bothered by one lousy score in a sample from a given school or that anyone will draw a correlation because his score and your [presumably better] one, unless he is normally a decent student and your teacher is perplexed by his performance and draws a connection between the scores and your seating assignments.
And how the heck did the seating permit him to copy anyway?
Dude I don’t think I can even call him my friend anymore. My school doesn’t have an honor code so I’ll just keep my mouth shut but I heard that the college board look over tests and see if your answers match oddly and they’ll flag your test but I’m not sure
They may be more sophisticated in terms of matching scores/answers to seating assignments that I was giving them credit for, but your first sentence is, unfortunately, very true. I’m sorry you’re in this position through no fault of your own. Good luck from a 66-year-old dude. 
As I said, the MC portion is scrambled. So while all the questions are the same, they are in a different order for different students, so 4’ spacing is allowed.
And I do think that similar answers will be flagged, especially where the cheater, by law of averages,will have more wrong with a similar pattern. Now if the cheater only copied a couple of answers, I doubt that a red flag will go up at the CB. Regardless, from a CB PoV, I’m not anticipating consequences for the OP.
Thank you!
One last question, do you think they grade tests after the score has been canceled?
If the score is cancelled now, the test will not be scored.
@skieurope : Your answer at #1 was not showing when I posted my thoughts. I yield to your superior knowledge.
I would not go that far. 
You cannot control the actions of others. All you can control is your own.
Next time work to keep your scantron covered. And this is his problem, not yours.
And cheaters cheat… over and over again. I would absolutely reconsider this friendship.