Fearow

Type Tier
Normal / Flying UU
Statistics
Stat
HP
65
333
Atk
90
278
Def
65
228
SpA
61
220
SpD
61
220
Spe
100
298
Name Item

Subbing Fearow

Leftovers
Moveset
~ Drill Peck
~ Return / Tri Attack
~ Substitute
~ Hidden Power Ground / Hidden Power Fighting

It's pretty basic here. Predict correctly and get a Substitute in, and then attack appropriately. Skarmory owns this, but Fearow can't expect to beat it anyways. Use Return for pure power or Tri Attack for pure haxing (if you're lucky like that). The Hidden Power lets it hit Rocks and Steels.

Name Item

Sleep Talk

Leftovers / Mint Berry
Moveset
~ Rest
~ Sleep Talk
~ Double-Edge
~ Drill Peck / Hidden Power Ground

Rest and Sleep Talk keep Fearow alive after it takes recoil damage from Double-Edge. Drill Peck is there to mostly hit Ghosts, but it also gives a nice second-STAB for stuff that it hits super effective. You could use Hidden Power Ground in that last slot for Ghosts, Rocks, and Steels.

Other Options

Fearow can use Mirror Move to send back Earthquake on something random like Nidoking or Golem (after switching in on it, of course) is funny as hell. Pursuit could be good for a laugh on something with low HP that tries to switch if it can't beat Fearow. You can try out Curse to boost your stats, but then you lose your major strength: Speed.

Opinion

Fearow is a decent UU Pokémon, but it just has too shallow of a movepool to be overly useful. The Advance generation did Fearow a bit of a favor by giving it Choice Band to boost that decent attack it has, but in GSC, there's no reliable way to get that kind of offensive boost to Fearow without hurting its usefulness. Another thing that hurts its usefulness is the presence of Dodrio, which outclasses Fearow anyways.

Counters

Rock and Steel-types with high Defense wall Fearow indefinitely, even if it has Steel Wing or Hidden Power Fighting. Electric Pokémon in general switch in easily on Drill Peck and hit Fearow super-effectively, as do sturdy Waters carrying Ice Beam. Cursers will usually win against Fearow provided they don't suffer a critical hit. Gengar isn't a fan of getting hit by Drill Peck, but is immune to Return and has Thunderbolt.