What kind of engine does a pontoon boat have, and what type of gas does is take?

Depends. Tri toons will come with 90-150-175+ HP. Now a regular pontoon newer may have a Johnson 40hp-50hp and most with a Mercury 30-60hp. There are outboards, and also inboards. Outboard is where the engine is above water but the prop(propeller) is under. Inboards are completely underwater, but you will get IO(inboard/outboard) That is where its more like half/half but looks like a inboard. Most pontoons will have outboard. The ones with inboard are over 150hp and are more for ski pontoons.