I've played that game on Wii for over 1000 hours!

It was my favorite before Dust.

I got Diablo on PS3. It's enjoyable and well made.

I thought about it, but Dust takes almost all my free time now.

Yes, Dia-Blos, as in two horned. [...]

Doh!

If you have some kind of cover on the map, use it. You have to stay clear of him. Make huge demi-circle to flank him and be always prepared to avoid his charges.

From what I remember, Lances are good against that monster. Just time your attacks and stay far when it isn't time to charge.

There was something used to stun him, but I can't remember what.

I wish I knew why I found him so hard. Like I said before I may have just been using incompatible weapons, but I have yet to finish forging my Gunlance to check. I suppose every player has that one monster, and Diablos and Black Diablos might be mine...

Great little niche game series made by Capcom, a boss fighter of sorts. Just curious if anyone else here plays it. Also, any tips on fighting Diablos would be nice, the things have been my bane for years...

Why should you pick up a Monster Hunter game?
http://www.youtube.com/watch?v=lF3zYmr1jOA

This giant Elder Dragon swims along, doesn't even feel your steel biting into it's flesh. Then you give it an unwanted trim and IT'S ON!

in MHFU, mine was the Black Gravios. Could never figure out how to get away from that beam-sweep attack. When i did kill him, it was either with a team or by spamming every bomb and paralysis-inducing item I could carry.

Thanks, I may just be using the wrong weapons. I specialize in Switch Axe and Dual Swords with a minor in SnS and Heavy Bowgun, so I'm probably just gimping myself.

Out of that list, I would take the Heavy Bowgun, fit the Shield attachment, and carry as many Shock Traps and Sonic Bombs as possible.
Using an HB, you should be focusing less on jamming its horns in the wall, and more on bombarding the head with Crag S - the stunned status lasts far longer, and the stun damage stacks with Hammer hits when teamed up. The Shield is there because you aren't able to dodge very well with the HB unsheathed. Of course, always carry Normal L2 when your other shells run dry.
Other shot types to use:
Sleep S: when a monster is sleeping, the strike that wakes it deals 3x damage. Put it to sleep, then shoot at a Large Barrel Bomb+ to do serious damage.
Pierce: Aim just below the head when he faces you, or across the wings to ensure the shot travels through as many body sections as possible. At close range with no Pellet, shoot through the leg up into the opposite wing.
Normal S lvl 3: L3 ammo ricochets off whatever damageable item or monster it hits. Aiming for the belly or legs can cause multiple hits, as well as shooting the frill from behind.
Pellet: There's something about Diablos that just makes it easier to hit with Pellet rounds. In some cases, I use it even more than Pierce for its damage potential
Elemental: I don't think Diablos is particularly weak to an element, but I always used Thunder and Water S because they behave like Pierce shots do, which is good when your Pierce S runs dry.
Para S: if your HB can fire it, take it. 8 L2 shots will paralyze about twice, carrying L1 will let you paralyze probably another two times.

Some of these have changed overtime, or at least for the third season. MH4 just came out, so no idea what they are there yet. For example, the Mega Drugs need Pale Extract, a drop from the Flying Wyvern Gigginox, instead of Honey. They probably thought it was too easy to get them with Honey :3
Also, Ancient Potion is now Kelbi Horn + Immunizer. Immunizer increases red health regeneration speed, and is a Dragon Toadstool and a Catalyst. Furthermore, traps are now used abit differently. Some monsters, like Nargacuga, are too smart to fall for a pitfall trap unless they are enraged, so a Shock Trap works better for them. Shock is also the only trap to use in underwater hunts. Furthermore, some enemies react especially to traps, like a Zineogre will steal the charge from the Shock Trap and go into rage mode, an Agnaktor's lava armor will soften when it falls into a pitfall trap and the magma beneath it, and a Glacial Agnaktor's permafrost armor will re-solidify if buried in the ice via Pitfall. And yes, it is Thunderbug :3

Derp, Ancient Potions always needed Immunizer. I'll update my post straight away.
Also derp, i think the mega Drugs always needed Pale Extract - they used to drop from the Khezu, so it's interesting to hear it drops from a new monster now.

Narga's always done that, and it's also notable that you have to enrage Narga to cut the tail. Also, they're quite susceptible to a well-timed Sonic Bomb.
I'm guessing the Agnaktors you refer to were originally Akantor and Ukanlos in MHFU?