I started with a few tomato seeds indoors in 1"x1" pods. Once the seeds germinated and the seedling was a good 2" tall, I transplanted these to 4" pots. From there, after it was about 6" tall, I transplanted them to my raised vegetable bed. Some of the transplanted plants are doing well and starting to bear tomatoes. There are two in particular that look perfectly healthy (looking green and all) but are not adding any new growth. No new leaves or flowers and they are still the same height as they were when I planted them. I have fertilized and watered them regularly so that is not an issue. What could the possible reason for this behaviour and how can I reverse it so the plant starts growing? I can post pictures later but this has been bugging me for a few weeks.
Simple, those plants need to produce roots in the new and larger soil available..to support the obviously future larger top growth. The growth is under the soil where you can't see. One of the reasons it is wrong to transplant small plants into too large of pots. Relax. Make sure you are using fertilizer that is lower in Nitrogen than Phosphorous and Potassium. Do not overwater tomatoes like to dry out a bit.
When transplanting make sure you 'fruff' the roots a bit. Pulling out roots to learn a new direction, cutting a few. Also stimulates better root growth.
I'm going to provide an alternative answer. This is from John Jeavon's book, and other sources.
Seeds should be germinated in 6 inches of soil. This gives a large root mass and makes it easier to transplant. Seeds should be broadcast onto the seed mix, and when the first true leaves appear, you then select the best seedlings from these to transplant again.
You lift the seedlings by their true leaves ( don't disturb the stems or roots ) and transplant them closely into another 6 inch flat. By closely planting your seedlings, you ensure that the soil mix has enough roots to remove as much water as possible so that air is drawn to the roots. Having a deep flat means that the roots don't hit the bottom early as in some plants, that sends a signal to the plant to stop growing. So, that's an issue using small pots to grow seedlings in. Transplant into the garden when they're 6 inches tall. The doubling handling seems to stimulate more root growth vs just seeding straight into the garden.
So, your transplants may have insufficient roots when transplanted so are now catching up, or, may have been stunted by growing in too small a container.