There are a number of lists for Companion Planting and one I use is at the URL below. They list Onion Family, Nasturtium, Marigold, Asparagus, Carrot, Parsley, Cucumber as being compatable with Tomatoes and say do not plant Irish Potato, Fennel, Cabbage Family with them. Here is a link that might be useful: Companion Planting

I've heard that marigolds are great for companion planting with tomatoes; not to eat (unless they're etible & I don't know it), but more as a bad-bug preventor. I can't remember if the marigolds draw the baddies away from the toms, or are poisonous to toms or what, but that's what I read in my veggie OG handbook. It also mentioned that one commonly accepted companion was not as good as people thought; sorry I can't remember which one (maybe if I knew more about gardening). I'll try to remember to look in the book tonight. I've also heard, but don't remember where, that peppers & toms aren't so good together because of similar susceptibilities & also both heavy feeders. I'll try to find something about that, too.

Size of plants? If transplants, perhaps cutworms? (They work at night.) If larger/older plant, please post image.

No offense intended but I think you will find that "companion planting" isn't a widely popular approach. It is considered a very minor school of thought, a fad, by most experienced gardeners. So if you are interested in learning about it, by all means do so, but please understand that you won't find it frequently discussed on general gardening forums. That is why they have their own forums and info sites. In my personal opinion, based on some 40+ years of gardening, the problem with your broccoli is that while it can leach some nitrogen from your tomato plant's soil it is minimal and can be easily replaced. Your broccoli was simply planted far too late in your zone. In our zone, when the time comes to plant tomato plants the broccoli should be almost ready to harvest +/- a couple of weeks. So when proper planting times are used, they pose no problems for each other. At this late date it is too hot for it to form a head anyway so you might as well pull it. The marigolds are a whole other problem as they attract aphids and whiteflies which then infect your tomato plants. That has been discussed here and a search of this particular forum using 'marigolds' will pull up the discussions about all the problems they cause. But if you want to practice companion planting then your best source of info will be their forum and their info sites. Dave Here is a link that might be useful: Companion Planting forum