I minimize my tomatoe sauce usage, I'm not big on tomatoes to begin with. Also I don't eat raw veggies due to gas issues.
I had good luck feeling better on the Low fodmap diet but I hated the restrictions on food.
Everyone really is different and it will take time to see what works for you. Even quantity of each food daily can make a big difference.
As far as what caused pouchitis, I think it's a lot of things. Basically my Dr said already having gone through UC and all the issues involved with that it's likely for us jpouchers to develop pouchitis and once you have it's more likely to reoccur.
I'm sure sugar is bad for everyone as bacteria can really feed off it and quickly make things worse.