How they can be incredible if they are poor altcoins? Well, I mean that those descriptions are contradicting how you describe it. Going on, it's possible to short from another exchange to another.
I think what he meant is Incredible Volume so poor in value because so far it is Rpple (XRP0 who's having huge volume but stays in top 5.
Do you mean arbitrage trading? it's possible and it's been done by many traders if the spread from the other exchange is quite high and you can see the potential profit. But, there's also a chance that you might be rekt if done it slowly and wrongly.
Well arbitrage is still profitable if you have experience,because all you need to do is watch each exchange and transfer your funds from each other that has High in value.
Shorting needs good volume, which most poor coins don't have.
With Lukc?it is possible but i'm afraid Newbie like OP can find that way to success.