For Mario, recovering against Snake is always difficult. Snake can go really far off-stage, because of his infinite recovery, so Snake could go deep under the map. Snake could also setup C4 on Mario before he was hit off-stage, and set that up into a back-air or a forward-air. Snake could go off- stage, and try to hit a fair spike or a stage-spike, or he could barrage you with C4 and grenades, and only come down once he gets a confirm. Both of these options are really good for Snake, and usually very safe. However, the safest option for Snake is to use his Nikita, and just home in on Mario. It's a option Snake will probably be using all the time because of my reasons, the biggest one being it requires no commitment. So when Snake does this while your off-stage, he's probably looking for a stage spike or confirm. As soon as you see this, recover ASAP. You could hit it with your up-B for it to become inactive, or go around it. Whatever our choice is, make sure it's unpredictable and fast
Mario