Punks, the tiny pony's on corn & oats too??
Honestly, grain hasn't got much in it they can't get elsewhere aside from high carbs for energy they don't need, so they should be even healthier without. Alfalfa is also very high energy, although it is low sugar. It's quite common for starchy diets to cause gut ulcers & such. I'd personally be just feeding hay & a (grain free) ration balancer or complete nutritional supp. And more exercise. Believe me, it's better to be proactive & avoid IR & laminitis than manage it once it's too late.