User blog comment:JusTSeaN/Guides/@comment-2036320-20100716195538

Diablos' weakness is sonic bombs. Use them when it digs (except when enraged), and it will get stuck halfway in the sand, letting you attack the head. When it gets unstuck it will hover over the ground for a bit, if you flash bomb it then it will fall and stumble. Rinse repeat as long as it's not enraged. There is also a pillar in Area 9 of the Sands where it can get its horns stuck during a charge (plus a shiny drop). When Diablos is enraged (huffs black smoke) make it your priority to evade its attacks. Use the panic dive when it jumps out of the ground, but don't use it when it charges because that leaves you prone if it turns and charges again.

Barioth is very annoying because it moves a lot. A lance or SnS is probably the easiest weapon to fight it early on. Don't bother countering with the lance because the barioth moves too fast. Block, wait for it to hit you, turn around and return the favor. Rinse repeat. With the SnS you can be more offensive, and use the shield as a last resort when it jumps at you. You'll still take some damage, but a little is better than a lot.

Another tactic you can use with the Barioth is pitfall traps. You can then use more damage-focused weapons like a hammer (using evasion-boosting armor is recommended in this case). When it's trapped aim for the wings first. I have no hard data to back this up, but I get the impression that breaking the wings lowers the damage taken (my guess is that undamaged wings crit more often). A side effect of breaking the wings is also that the Barioth will skitter when landing from a jump, buying you more time and slowing its attacks.