I'm lazy and hate hard maps however...

Yeah I've had way over my share of long hard puzzle solving and saving 1000x on some hard as hell Plutonia map. However using the Compet-n site and Opulent's sda, I never have to worry about missing out on fully enjoying a level(ok maybe partially as some of the compet-n runs are so fast you can't stop and smell the roses, but I digress). For example, I just got the final release of Hell Revealed 2, and as expected most maps are way too hard for me to handle. But using the HR2 demo set from opulent's sda I can see all the levels now!

Another thought I've kicked around is doing a level with the -nomonster setting on if there's too many monsters. Even with god mode on and full ammo if there's a 100 monsters in a room to kill, a bfg is too slow to clear all of them. So NO monsters is good.

Another way that I've had some success with is using slow-motion, but my keyboarding skills are so bad that even this doesn't work too much.

You just use Keyboard? Dude, if you think you suck, chances are it's just because of bad movement with the keyboard, I use a Track-ball keyboard combo in Legacy, here's my setup:

Turning: Track-ball
Moving: Foreward and Backwards Arrow Keys
Strafing: Left and Right Arrow Keys
Weapons: 1-7
Fire: CTRL
Always Run: On
Use: Enter
Jump (if available): /

Maybe that'll help a bit...

Convert to WSAD. It makes things SO MUCH easier.

Demos sure are a great way to see a map.... usually. (maxdemos anyway)

Have you tried taking the skill setting down to something easier? HR2 was made with the skill-settings well in mind... and Hey, Not too Rough is probably on par with Plutonia on UV...

HR2 (and similar wads) were really designed with the practiced, hardcore DOOMer in mind... there are plenty of excellent wads that aren't quite so challenging.

just my 2c

In my opinion most Megawad PWADs are designed to be harder than Doom 2 itself (or Doom) WADs like Hell Revealed and Alien Vendetta in particular are most likely designed for the Doomer that has at least completed [Doom,Doom 2] on Hurt me Plenty. Even Plutonia (or Evilution) is not a first time Doomers IWAD of choice to get skilled in playing Doom.

Opulent said:

there are plenty of excellent wads that aren't quite so challenging.

A few suggestions along those lines:
Icarus
Demonfear
2002: A Doom Odyssey (first episode)
TVR! <--- especially recommended in this context
Scythe (maps 01-10)
Real World

Extensive collections of demos exist for all these wads (at Opulent's DSDA site - click on "Single-Player").

I thought Plutonia was designed for co-op play only and impossible to play through on SP. I believe this because on Map02 or Map03 I think it is on Plutonia there's a point I can't get past no matter what. Maybe if I'm able to I'll make a demo and show you all what I mean.

That's certainly not the case - watch some compet-n demos to see how to get past whatever it is that is causing you problems.

One could argue, conversely, that Plutonia is unplayable for coop though, since map22 clearly isn't designed to be played in coop mode from a pistol start without dying (as Vince has pointed out).