It's hard to predict which out of thousands of alts will go up, but what you can predict is that once a coin went up, it's bound to go down. Like, take the best performing coin right now, Dogecoin, there's absolutely no justification for its price, it has no adoption or promising features, it's pure hype. It's bound to go down, so if you carefully short it with small leverage, you're going to make profit. Obviously, the danger is in the known trading wisdom - "the market can stay irrational longer than you can remain solvent", but still the fact that pumped coins will go down is something that you can rely on.
Like always the problem is the timing, we know that dogecoin will go down at some point in the future but it is growing so fast that you are going to be destroyed if you decide to short the coin right now, it is better to just wait and only try to do that move once dogecoin begins to go down.
After all when that happens that will most likely be a clear sign that the altcoin season is over and almost all altcoins are going to begin to move down at the same time, the only thing I would like to know is if this is going to be accompanied by bitcoin going down or it is going to still grow in value as people decide to sell their altcoins and buy bitcoin instead.