OK, since I'm one of the probably few people who's seriously tried to use Unown in GSC:
Gyms that it fairs well against: Falkner
Other info: Unown's only saving grace is the fact that you can catch one with a Hidden Power of any type, meaning that it can give some much-needed coverage early in the game; pick one with HP Ice, Electric, or Rock, and it'll help you beat out Falkner if you started with Chikorita. Its stats are too low to function meaningfully later in the game, though, even with super-effective attacks, and it cannot meaningfully be trained up because it badly needs coverage to score KOs.
Recommend this is placed into Bottom tier.
Pokémon spinoffs: Ranger You freak out when you hear a Clamperl; Mystery Dungeon You freak out when you see a Ledian.
<Sunflora> So let me get this straight: you're sending me into a dungeon full of lava, to capture a Haunter which is part poison type?