Well trying to grow all of those indoors is a whole other set of issues so putting all that aside for now, only the tomatoes and peppers need individual containers. The rest may be transplanted to individual pots or grown in clusters. Your choice. Many grow herbs and leafy greens in small clusters of 3-4 plants each depending on the size of containers used. So if all 12 seeds come up on them then you could transplant them into say 3 plants per pot.

When you get a chance you might want to do some more research on different germination methods here - lots of great how-to FAQs and discussions here. Using 6" pots to begin with isn't ideal by any means.

Good luck with your plants.

Dave

The alternative method of thinning is snipping. Small sharp point scissors used to snip off the excess plants at the soil line.

Dave

If the seeds were planted in peat based seed starting mix, the sooner they get out of it the better. Al