Monster Hunter X news
That owl can use(what appears to be) a yellow powder which inflicts a new status that reverses your controls. In order to cure this status you need to eat a bitterbug. The owl can also put you to sleep.
Mounting has been changed so that when you mount the monster, other players can hit the monster all they want, it won't knock you off(thank god). In fact, it's actually beneficial to hit the mounted monster in MHX. It makes it easier for the other player to succeed in the mount.
Also, when another player mounts the monster, a gauge is displayed under their name showing how close they are to toppling the monster.
The Aerial hunting style allows you to use monsters and other players as springboards and jump over them and allows you to attack the monster from above(this will not result in a mount, like the insect glaive's pole vault would). The drawbacks to this style are the following: the Aerial style's jumps have slightly fewer invincibility frames than a normal evade, and are a bit longer too. You can only equip 1 super skill, as opposed to the normal 2. You also lose some ground attacks, not necessarily the same attacks you would give up for the Striker style though.
Striker style is heavily focused towards super skills, and abusing them as much as you possibly can. You give up a lot of your attacks/techniques, and have the mechanics of your weapon altered in some way and are left with a simplified moveset which focuses on making you charge up your super skill gauge as fast as you possibly can. With this style, you can equip 3 super skills, instead of the usual 2.
Bushido style has not really been shown off much, but apparently, you only get one super skill when you use it, and it gives you something called a "perfect evade." Basically, if you successfully evade through a monster's attack, you will use a special move of some sort. This special move is different for each weapon.
If you don't know the monster you're fighting very well, the Bushido style is pretty much a worse guild style. Only equip this if you are confident that you can make use of the perfect evade attacks.
Edit: Lagiacrus is back, people(still no water combat, thankfully)!