I don't know how you're supposed to get to A rank in multiplayer. You need to win at least 1/3 of your matches, couple this in with completely random levels and comical lag. There's obviously skill involved, but actually winning is essentially a mini-miracle.
That said, I've run into quite a good number of multiplayer versus map. One was 1v3 focused, another was a vertical level where there were four equal areas with the same obstacles. There are a couple I've played that weren't designed for multiplayer, but somehow worked perfectly.
When I was at B rank and played other Bs I had win streaks more often than not and then I got put into A lobbies not even halfway through B rank, where I got rekt, loosing many times in a row. Then I got to play low Bs again which is when I started winning again. And the cycle kept going like this. It's so obvious what's happening. I hate hidden ranks so so much.
Here's a tip that helped me a lot: do not make any risky plays at all when the game style is one that allows you to grab the flag together with the person in front of you. You might not win, but you'll also not loose any points this way. Play it safe, and let the others make mistakes. When it's SMW or SMB3, just go for it, since you have nothing to loose.
Skill is definitely involved, but I would say when you are playing a level blind, it doesn't really matter if you're a kaizo master or a mediocre player like myself. Most levels are easy to actually play through. The deciding factor is to quickly assess what needs to be done in a given situation, i.e. should you go down that pipe or should I continue to the right? Will a piranha plant pop out from this pipe; should I wait and see or just jump? Is this a z-jump? Where has the creator hidden the final key coin? If you have the correct answer more often than your opponent then you will win, and this aspect comes purely from experience, not skill. The only way to get good at this is to simply play a bunch of these crappy levels over and over until you start seeing the patterns, and recognize what type of level it is based on early indications, and then be mentally prepared for what will likely happen next. It's only luck if the stage is short and easy, then the person who happened to make it out first wins, or if there is a bottleneck, like a boss room with a locked door, and you need to take out Bowser with fire flowers. That scenario is 100% luck based, since whoever gets the kill shot gets the key, and then good luck avoiding everyone trying to steal it. Whoever then manages to enter the door first is guaranteed the win because the door is always placed next to the flag. I totally agree that it's very awful to loose in this way.
Also: read the title of the level. If it says 1-1 SMB, then you know exactly what to expect. Being mentally prepared for what the level will be like is key to winning.
Multiplayer VS maps need to have comeback mechanics, because the game is most fun when everyone is packed together. A thing you can do is to include information based deaths. Stuff like hiding Yoshi inside an obscure block nobody will bother to check on the first go, then further ahead you place a jump that demands a Yoshi suicide to clear. The only way to know you need Yoshi is if you jump out towards the pit, realize there's no way to make it, and then die. Then you figure there must be something in the stage that helps you clear the obstacle and you start looking for it. The 2nd player will go ahead and do the same thing. Now here's the thing, the 1st player has respawned and is on their way to look for a powerup, so while they are looking, the 2nd player will catch up and they will look for the hidden block together. Voila, the gap between first and second has been erased. Or you could have situations where the player who reaches it first needs to do something to open up the path forward which will waste their time a little bit, while the path remains open for the others, resulting in a decrease of the gap between the players. Those are the kind of mechanics that bring out the most fun in multiplayer Vs I think.