The beats in hardstyle is usually called kicks, there's maybe 3 different major types of kicks;
Reverse bass: only used in this genre, mostly used in intros and outros
Gated kicks: not so much used anymore, more in early hardstyle
Kicks of FX kicks: Can be pitched or non-pitched (the tone of the kick varies), nowadays it's almost always pitched.
Hardstyle has very broad range of sounds, I mean what I linked there is some of the "rawest"/darkest **** you find and I personally don't listen to that style but what I call euphoric hardstyle that is more melodic based, happy or sad/uplifting etc. What hardstyle used to sound like in say 2004 (not to my taste) is very different to what it is today too, well should I say mainstream hardstyle, it doesn't sound so "hard" anymore at all and can be very similar to house music but with distorted bass (kicks).
Here's a Top-20 mix I made of some of my favs from 2007-2013, there's so many others I could also have thought of but yea this shows better the style tracks I like:
Edited by RPGWiZaRD - 6/30/13 at 12:38pm