Yeah I would say make your own with steel cut oats, a whey protein (concentrate, isolate, or whatever depending on your budget/tastes), a casein protein, and even some WMS.
But, if you were to grab a weightgainer I think that Real Gains has the best nutrient profile out there. Low sugars, plenty of carbs, nice amino acid profile(from multiple sources of protein), and even some healthy fats. I've used it and I liked it. Like Rodja said though, it would push you towards more of a dirty bulk. But from the sound of it, your brother can take it. I got the chocolate. It was not bad.
Plus the tubs make for great storage units of mass amounts of bulk powders. I saved mine and put my multiple tubs of WMS into one Real Gains bucket. The handle is a plus too.