1st Gen What part annoyed you the most in R/B/Y?

Definitely Rock Tunnel, because it requires the use of the most useless HM's in the game. You need to teach a pokemon cut to get to the cave and flash right after it in order to navigate through the cave. Of course you can also get through without flash, but it is way more comfortable with flash. Also I usually have to get back to the Pokemon Center halfway through because my pokemon took a lot of damage in battles or were poisoned.

Victory Road can be tough aswell. It's annoying to encounter Zubats/Geodudes every two steps; and you need strength. At least there are trainers inside the cave.

To be honest, the only issue I have ever had with the game was the hardware itself, I couldn't tell you how P'O'ed I was when I turn on the game and the save was gone, later found out that the internal battery tries up over time, but only with Red and Blue, because somehow the save function still works for me on Yellow, that I had for about 15 years now :D

I'd have to go with the Silph Co. and their teleport tiles.
Nower days it's an okay challenge, back then as a kid it was freaking hell

Toss up betwene the red graphics, and the viridian forest.

The one thing that really bugged me back then was the item limit <<; a lot of the times I'd end up running out of space ^^;

If we are talking about game mechanics, it would have to be all the glitch moves, focus energy lowering your crit. ratio, permanent freeze. For areas in the game, Silph Co. That is the most confusing area in any pokémon game. I can still never fully remember the correct path.

The last few caves/dungeons at Seafoam Islands, Cinnibar Mansion and Victory Road. It was as if there was no through, or out of SI unless you got lucky

Seeing:

"Nope! There's only trash in here. Hey! The electric locks were reset!"

Killed me a little inside.

When you would be walking through a forest, field, or a cave and the same pokemon keeps attacking you.

Navigating through Rock Tunnel without flash was a pain X_X.

Something I learned about pretty recently actually. The fact you could get a PokeDoll and be able to bypass the entire Celadon Game Corner part of the game. With the PokeDoll, you can go try and battle the ghost Marowak and use it, which causes the game to think you beat it. A very small oversight, but still grinds my gears :P

Silph Co. That place is so large and confusing. Especially when combined with the bad graphic, it's gets even more complicated.

Flash being rendered useless since there is only one place where it is usefull (actually no there isn't) also if you teach it to a Pokemon it couldn't forget it. Always switching Pokemon so they could get a decent amount of exp, since EXP-Share was pretty useless. Scyther being only catchable in red version (since I had blue and didn't know anything of the Mew glitch)

Bind and Wrap and all caves. What with their "three-step; battle" thing that STILL happens in current installations today.

My game freezing after leaving it on standby for more than 5 minuets. Or the cartridge coming out and the game re-setting it took me forever to get to lavender town...

Lack of repels... enough said?

Lt. Surge's Gym (3rd). It was just to annoying trying to literally guess my way though

When your bag is filled with Key Items that can't be disposed, so whenever you find an item you can't collect it because your bag is always full. That is why I can't stand playing Gen 1 games (and the fact that I can't save anymore).