RNG stands for "random number generator," which is basically what makes the computer players' AI do what it does at any given time, ie: There's no set pattern. Sometimes the AI will be easy for a stretch, sometimes it will block/reverse all your moves without you being able to do anything about it. As for the specials, if you activate your specials it only lasts for a handful of seconds before your spirit meter goes back to low green. If you don't activate your special it stays at a much higher orange color, and in this game the higher your spirit over another player, the more likely you are that your move is going to work against them. You want to maintain the highest spirit possible without going back down to green.

For survival mode there is only one default difficulty, so you're at the mercy of RNG for the entire run.

@@NintenJo-Power What is "RNG"?