So I'm just starting out with MH4 (just unlocked Expedition missions) but are there any tips to mounting? It feels so incredibly frustrating and obtuse.
Mounting tutorial. There are 4 ways to mount that don't involve weapon specific skills.
About ledges, any ledge that your character will contextually jump off of is high enough to potentially mount a monster - very tall monsters seem harder to mount off very small ledges in my experience with the basic jump attack.
1. With your weapon sheathed - sprint towards a ledge of any size your character will contextually leap while sprinting - additionally (because you are sprinting) the range from the ledge that your character will leap is increased. Simply X - or some variant like R+X+A will be the draw attack options for most weapon types. The important thing to the sheathed jump attack. Sprint, no button required to jump. Attacks limited to those that will draw the weapon.
2. With your weapon drawn - near any object that will allow the b button to be used as a "jump" in context. Unlike the sheathed attack, you have to hit the b button to contextually jump. Its range from the ledge will be less than the sprint. Basic jump attack - possible mount.
3. With your weapon Sheathed you can climb many walls A grabs the wall. If you have no input on the left stick while on the wall and press A, your character will spider man jump off the wall straight out at whatever direction the surface you are on is pointing. This can be used to mount by initiating a jump attack (unsheathing the weapon). Your character also is quite the athlete and can jump quite far away from the walls.
There are two more special cases. The first is useful to every weapon, and is super fluid and feels awesome to use.
4. With your weapon drawn. If you use the B button to roll into a climbable wall with your weapon out and hit A while mid role and touching the wall - your character will climb the wall in one maneuver. It is a smooth roll into weapon sheathed state on a wall. Which you immedately follow up with a deadstick A press leap off the surface into a quick jump attack for a point blank wall mount. It happens very fast and can be used to very successfully mount monsters that are against climbable walls. The roll into climb is also an extremely good way to climb ledges to position yourself for sprinting attacks and more rapid evasion as most monsters will scrape you off walls with some kind of attack if you linger too long.
5. These are contextual to weapons. For example. When the dual blades are charged up - there is a spinning ledge attack that is this big leaping spinning animation - that attack will mount. Likewise the longsword - Once you charge the weapon to at least its white spirit level - it unlucks this jumping X slash attack with the R button - This attack can also be used to mount when jumping from a ledge. I do not know all of these - but its worth noting that they exist.
Couple more details about jump attacks. There is definitely a cooldown or resistance to being mounted for every monster. You can most definitely mount everything more than once a fight. Jump attacks are still valuable tools between being able to fully mount the monster. A jump strike to the head or the "mount" spot can create a monster knockdown - where they flail for a much shorter time than a full mount - but they hit the ground for some free strikes or access to hacking body parts with a combo. Aim for the sweet spot to mount each monster is a little different. Taller/bigger monsters can be harder to mount because if you don't jump attack precisely you'll just do damage to a body part but will not mount. Keep in mind that every weapon (I think) has moves that will disrupt allies and knock them down/kick people out of monster mounts while some attacks can be used - if the monster stumbles from the damage you do it will also break the mount and that sucks too. So when you do play multiplayer wait till its on the ground, and tell others to as well if they are not.
