Will doing 200 crunches a day help make my stomach stronger?Simple answer, No.
Crunches don't make them stronger, and are probably not the best ab exercise.
Things like compound movements make the core stronger, then planks, rollouts, farmer carries, and pallof press to name a few will make the core strong.
Check this out, and you will get a free eBook. These are five great exercises to start with and build from there.
If you have anymore questions, please ask. Rossy@mattrossignol.com