Water-type Pokemon are weak against Electric and Grass-type attacks.
Water-Type moves are strong against Fire-Types, Rock-Types, and Ground-Types. Water-Type Pokémon are strong against Fire-Types, Ice-Types, Steel-Types, and other Water-Types.
They are strong against Grass, Steel, Bug, and Ice.
Dragon-Type moves are only strong against other Dragon-Types. Dragon-Type Pokémon are strong against Fire-Types, Water-Types, Electric-Types, and Grass-Types.
Electric-Type moves are strong against Water-Types and Flying-Types. Electric-Type Pokémon are strong against Flying-Types, Steel-Types, and other Electric-Types.
Water-Type moves are weak against Grass-Types, Dragon-Types, and other Water-Types. Water-Type Pokémon are weak against Electric-Types and Grass-Types.
Grass type Pokemon are strong against Water, Ground and Rock.
Grass and Electric can defeat Water types easily.
It is a matter of opinion. Chikorita is a grass type, so it is strong against water, ground, and rock types and weak against fire, ice, poison, flying, and bug. Cyndaquil is a fire type, so it's strong against grass, ice, bug, and steel types and weak against water, ground, and rock types. Totodile is a water type, so it is strong against fire, ground, and rock types and weak against grass and electric types.
Bug-Types are strong against Psychic-Types, Dark-Types, and Grass-Types.
Pupitar is a Rock- and Ground-Type, so it is weak against Steel-Types, Ground-Types, Fighting-Types, and Ice-Types, and exceptionally weak against Water-Types and Grass-Types.
Ice types are supereffective and so are dragon types. Yes, dragon types ARE EFFECTIVE against dragon types. In some dual-type dragon pokemon, like Garchomp for example, Ice is 4x effective to it and Dragon types, 2x
They are strong against a lot of types. They are weak against Fire, Fighting, and Ground though XD. They are also weak against water types.