@ Black Glasses
Feint Attack
Confuse Ray
Toxic
Moonlight
He's useful for snatching and stalling out the opponent. Feint Attack is there so he has something to attack with.
@ Twisted Spoon/Spell Tag
Psychic
Reflect
Shadow Ball
Morning Sun
Reflect because you get Earthquake spammed later on. Shadow Ball was Physical at the time, so you may want to consider Spell Tag instead.
@ Amulet Coin?
Thunderbolt/Thunder
Thunder Wave
Light Screen
Focus Punch/Rain Dance
Magnet isn't available, so give it what you think is useful. Give it Rain Dance if you learn Thunder for better accuracy.
@ Mystic Water
Surf
Ice Beam/Blizzard
Brick Break
Protect
You can choose between three starters early on, and I chose Croconaw. It comes with Mystic Water to boost Surf.
@ Black Belt
High Jump Kick
Detect
Reversal
Recover
For a fighting-type, it's a battle between Makuhita, Meditite and Hitmontop.
Hitmontop can support with Intimidate.
Hariyama has survivability with Thick Fat.
Medicham is strong with Pure Power.
@ Soft Sand
Earthquake
Screech
Fire Blast
Crunch
It arrives a little later, but it quickly evolves into Flygon with the useful Levitate ability.
TRY-HARD TEAM:
Rock Slide
Earthquake
Crunch
Return/Hyper Beam
Tyranitar is the most powerful non-legendary in the game. Just keep in mind that Crunch was Special at the time.
Meteor Mash
Earthquake
Psychic
Pursuit/Protect
Metagross has beastly stats and a great defensive typing. It has no 4x weaknesses, so it's hard to KO.
Rain Dance
Thunder
Crunch
Reflect/Calm Mind
Raikou is fast and one of the best special sweepers in the game.
Calm Mind
Surf
Ice Beam
Rest/Rain Dance
Suicune is hard to KO and even harder to stop once it gets rolling with Calm Mind and its high defenses.
Sunny Day
Fire Blast
Solar Beam
Calm Mind
Less fragile than other fire-types.
Megahorn
Focus Punch/Brick Break
Reversal
Endure
Heracross isn't considered because it arrives very late in the game. Nonetheless, it is one of the most feared Pokemon and many of its counters can lose to it.