Well, for regular non-boss enemies, I'll have to go with the iron-shielded fat moblin because he uses up 5 arrows with the fully-powered bow (10 regular ones) and I don't know how many dozens of sword slashes. He depleted me completely of my arrows when I did a certain escort mission for the first time and that forced me to go back, upgrade my bow, buy another quiver and upgrade that as well.
For combos, I hated that room in the sandship with the 3 beamos statues. Alone, they are one of the easiest enemies ever, but if you have to battle 3 of them simultaneously without a dead spot to hide in, things get very ugly...
Another one that kept annoying me is that 3-eyed sand worm. But once I learned to backflip just in the right time this was a piece of cake.
On a side note, I really can't understand how so many people are having such huge troubles with the sandship mini boss. I mean all it takes to defeat him is stab-stab-stab[...]-occasional shield bash/backflip-stab-stab[...] till he falls of, rinse and repeat. The only difficulty is noticing when exactly to do the backflip/shield bash but if you pay close attention that shouldn't be a problem. I found almost all of the other mini bosses harder (notice that "hard" is relative here), like for example the 4-armed stalfos (because unlike in the pirate battle you have to constantly change the way you swing your sword) or the stalfos/skultulla combo (optional miniboss during second Skyview Temple visit). When I went after the stalfos, the skultulla would catch me in the net, making me vulnerable to the stalfos' attack. When I tried to swoop the skultulla, the stalfos got in my way...
Speaking seriously and without previous experience, I think the hardest would definitely be Ghirahim for the unseeing eye. He isn't exactly the most random boss, but some people just have so much trouble that he'll wipe you within seconds.
With experience, I'm thinking the Lizalfos would be the hardest but then again...they're just slash slash enemies that do little more than cower behind their gauntlet of awesomeness.
the technoblins, these are the one that took me the most hearth.
i also had some problem with the wooden shield moblin for the fact that if you break their shield they get new more which are harder to dodge (the metal shield have more health but you can`t break a part of teh shield by accident and then be forced to fight them in their 2nd form
If Link lost hearts when falling off cliffs, I would say Moblins for sure; whenever I fight one with a sword on a narrow ledge, I'm guaranteed to fall off at least two or three times...I'm sorta thankful for taking no damage each time that happens. I guess Technoblins, because I'd get electrocuted through bad timing, then promptly hit their zapping thing again as soon as Link can move after the first electrocution.
Id say the Iron shielded moblins were the hardest till i finally figured out how to kill them with the sword in the end of the game. Also, id say the final boss was the hardest person couse of his second phase. But again, once you learn the technique to kill him the entire battle became easy.
So far I must say that prior to getting the bug, it was a pain getting the skulltula turned around so that I could actually kill the damn thing. I hate to admit it, but I was taken out so many times before I finally worked out how to nail the bastard. Once I got the bug, however, they were dead easy.
I also struggled with those tower-thingies that shot out electricity, simply because I hadn't perfected the stabbing motion with my controller (Link kept slashing from above instead, which got me killed a couple of times) - but once I perfected the stabbing motion I never again had trouble with these towers.
I've only just finished the battle with the creepy monster we saw in the dream sequence in the beginning of the game, so I can't say yet which enemy I find the hardest, cause so far it's been a matter of figuring out the right motion and getting control over that specific motion. The enemy is highly challenging right away, but once I perfect the motion the enemy is dead easy to handle...
Stalfos, in regular and knight forms. I've been able to form up correct patterns of sword slashing for all foes, these being no exception. Nonetheless, this doesn't detract from the number of hits it takes to destroy them. Also, when they do manage to land a blow on me, the penalty isn't light.
i have no idea the name of the enemy i find the hardest. they're those big heads, you need to use the gust bellows to blow on the propeller on top of the head. they always get to me before i can finish blowing on the propeller
Took me awhile to figure out how to kill the flying drones (with smart bombs and rockets)...so that thing killed me once. The most annoying to me were actually the gold deku babas. You had to guess if it would open horizontal or vertical, and if you waited to find out you'd miss your chance. Later, I just beetled 'em.
dude!!!!!!!! those bokoblins with the tazers SUCK. I HATE THEM SO MUCH. hhhnnngggg. i LOVE fighting the lizalfos, they have always been my favourite enemy in all the zelda games. they aren't *hard* to beat though. Those tazers, man. Technoblins make me want to blow up the earth.
Skultulla (took me a while to figure out how to make them spin)
Lizalfos (in the beginning, once you know how to hit them they're not that though, but I figured it out near the ending of the game )
and Ghirahim, out of 20 swings I get 1 hit