Yes, plenty. I'm currently growing 6 plants each in a 12" pot under 250w lamp. I'll let them get to about 1 foot tall before I flower them. There's no point growing them any bigger than this because the light from 250w doesn't penetrate foliage very far, it would be a waste of time and effort. You can grow about 24 plants under 250w but you'd have to grow them in 6" square pots and flower them when they're about 6" tall and left unpruned so they have just one main cola. You'd probably have to swap the plants on the outside with the ones directly under the lamp every couple of days or so, so that they all get their fair share of light.
4 plants is a good number to grow under 250w.