You can bombard Snake with so much projectiles and z-air. For him to get past this, he has to come to you, and his Hand Grenades aren't too much of a problem. He might throw them at you to distract you, or he might Snakedash toward you, but really, it's about the close-combat that Snake has more of an advantage. You want to get into the match at times, and then at other times move back to get some space. I think I need to learn how to fight close up, because I can do very well when I am at a distance, and because I'm not as strong close up. If you and I practice to get close up when it's necessary, we'll do a whole lot better.
the problem is erow (sorry, my mistake earlier) is VERY effective against samuses, he knows a lot better than most other snakes how to liimit samuses spam use. I actually don't have as much trouble with most snakes due to their samus experience, in fact, in the last tourney we played i actually was able to pull off wins against two snakes after i played and lost to erow's snake, however i do think that this matchup becomes 65-35 imo if the snake has legitimate samus experience. most snake's actually have trouble with samuses spams, but experienced snakes i find can limit samuses spam use by a lot. for example he can go under most zair use and forces samus to homing missile spam with crawl, and shielding, when this happens he can gain ground fast. he can also force lapses in samuses spams by using nades and use this lapse to gain ground, and of course he will be able to get heavy damage shortrange since like his moves do way too much damage @.@. he can limit samus' ledge options with grenades as well, and use the grenades as counters close range, and he can take advantage of samus from grabs as well.
snake usually has trouble off ledge against samus, however most snakes with samus experience will use the range of his cypher to fully go around samuses spike range and get back to the stage. when this happens snake gains like a 50% advantage due to the fact that he is heavier than samus and can ko samus way earlier onstage than samus can ko him. also, samus can't gain much advantage w/ battlefield either
which makes me sad, since snake does so well there..
samus isn't by any means helpless in this fight, i just think that it becomes sort of uphill for her and you are forced to play ledge and long distance more than usual. of course its important to take advantage of opening in his defenses close range and play short range smart as well, i just think that on the whole you are going to be more cautious when in those situations, since the risks are a lot greater.