Noctowl
Type Tier
Normal / Flying UU
Statistics
Stat
HP
100
 403
Atk
50
 198
Def
50
 198
SpA
76
 250
SpD
96
 290
Spe
70
 238
Name Item

Pseudo-Passer

 Leftovers / Focus Band / Brightpowder
Moveset
~ Hypnosis
~ Reflect
~ Night Shade
~ Rest

This can be pretty effective when used right, actually. Hypnosis what you can't beat, Reflect up, and use Night Shade on random things. Rest when needed, and run when any Normal Pokémon shows up.

Name Item

Physical Attacker

 Leftovers
Moveset
~ Hypnosis
~ Curse
~ Return
~ Rest / Hidden Power Flying

Physical Attacking. Once again, Hypnosis anything that may counter it, Curse up, and hit stuff.

Other Options

Faint Attack is a good option because 250 Special Attack isn't exactly horrible (though it isn't great either). Growl might be fun against Cursers, and Mirror Move might surprise someone. Whirlwind should be used with Reflect since 198 Defense hurts. Nightmare isn't a bad idea with Hypnosis, and the large amount of Rest+Sleep Talk in GSC. Nightmaring those Sleep Talkers will make them think twice about Resting again.

Opinion

Noctowl isn't bad, it just doesn't excel at anything in particular. It has tankish stats (403 HP, 290 Special Defense, and Reflect for its 198 Defense). If played right, Noctowl can be a real pain in the underused metagame.

Counters

Physical attackers, Sleep Talkers, Rock/Steel Pokémon, Normal-types, as well as Electric Pokémon. Yeah, Noctowl isn't going to hurt all that much.