If I understand your question correctly, Dark, Psychic, and Grass are weak against Bug.
Natu is a Psychic and Flying type Pokemon it is weak against Electric types, Rock types, Ghost types and Dark types.
I assume that you are referring to Fighting-Type Pokémon. When attacking, they are weak against Poison-Types, Flying-Types, Bug-Types, and Psychic-Types, and ineffective against Ghost-Types. When defending, they are weak against Flying-Types and Psychic-Types.
Personally, I would train a Bird-Type Pokemon at a place where those types of Pokemon is very effective to it. Like Fighting-Types. They are weak to Bird-Types. So, I would train it there!
usally fighting and bug (depends if it has a second type)
ONLY ground types. however, some ground type pokemon, ( like cubone or marowak ) have the ability "lightningrod" witch prevents electric type moves for effecting them. electric types don,t effect ground types anyway.
Psychic Pokemon are strong against fighting and posion types, but they are weak against dark type. The best basic psychic Pokemon is Alakazam
Water type Pokemon are weak to electric type Pokemon.
Natu is a Psychic and Flying type Pokemon it is weak against Electric types, Rock types, Ghost types and Dark types.
Rock and ground. Flying, water and sometimes bug Pokemon are weak against it.
Psychic types are weak against dark and ghost But Pokemon like bronzor or brozong are weak against them because they are still types But a Pokemon like Gallade a Psychic-fighting type will be weak against dark ghost AND Flying types hope i helped
Axew is a Dragon type pokemon, weak to Dragon (WA?) and Ice types.
Ghost-type Pokemon are weak against Ghost and Dark types.
Grass type Pokémon are weak to Fire, Flying, Ice, Bug and Poison. Ground types are weak to Water, Ice and Grass. So both types are weak to Ice.
Bug type Pokemon are weak against Fire, Fighting, and Flying. Not fighting there not weak against fighting types, there weak against Fire, Flying and Rock.
Weak: Psychic Strong: Fighting
Fighting-Type moves are weak against Poison-Types, Flying-Types, Psychic-Types, and Bug-Types. Fighting-Type Pokémon are weak against Flying-Types and Psychic-Types. My best guess would be leaf Pokemon but Ihavent played it in a while They are pretty effective against normal type Pokemon.
Steel type Pokemon are weak to Fire, Ground, and Fighting, so those types of Pokemon will do well.