Thanks for the input! So far no aggression.
I feed Marshall by his feeding ring and he gets pellets daily, ill feed him those and crush up a few flakes to keep the tetras busy, otherwise they steal his pellets, but Marshall also snacks on the flakes and that takes a few minutes to them to finish.
So far I feed blood worms each 3rd day and swish a few to the lower part of the tank so they sink near the pea puffer, and I watch to make sure he gets a couple. Ill feed the Betta as far away as possible and he gets bloodworms first to attract the tetras to his side. My puffer has been lookin fat from all the pond snails he has gobbled up this week. Only a few large snails left!