Haymaker was good until the Neo generation came around.
There were LOTS of strategies, these are just ones that I can remember.
Base set - gyms ear there was: (Monthly type era)
Haymaker
Alakazam/Tentacool
Wigglytuff & Clefable & Ditto decks
Some decks ran Fossil Muk, others Fossil Aerodactyl
Blastoise/Gyarados
Silly Mime Variants
When the Neo sets came out: (Monthly type era)
Slowking decks
Sneasel decks
Feraligatr/Parasect
Typholosion/Moltres
Jumpluff
Meganium/Exeggecutor
Umbreon (sniping)
Kabutops
Steelix variants
Dark Feraligatr was played
Tyranitar/Unown D/M/N
Entei/Magcargo
When the Ereaders sets came out: (Battlezone Era)
Arcanine
Venasaur (energy acceleration)
Tentacruel/ Dark Espeon
Xatu
Crobat/Noctowl
Beedrill/Muk
Scizor/Muk/Furret/Mantine
Light Dragonite/Boost energy
Charizard/Electabuzz/Boost energy
I could get into the specific strats upon request from anybody. Otherwise that would be a lot of typing for me. :/