3rd Gen Pysduck or starmie

i doing a play though on fire red and i was trying to find a good water type and i don't want lapras who should i choose.

Starmie is usually the better choice. It's movepool is very diverse. You can always run something like: Psychic, Surf, Ice Beam/Recover, and Thunderbolt. Psyduck is a very unique Pok?mon and it's worth trying out if you'd like something a bit different from the norm. It can be run Physical or Special. It's movepool isn't as quite diverse though.

^

Starmie has great speed and special attack. Also psychic types are very powerful in that generation, and Starmie has a very diverse movepool.

Starmie and Golduck both learn Psychic through TMs. The difference is Starmie gets STAB with it and it also learns recover. Plus it's pretty darn fast so that would be my choice.
I'd probably choose it's moveset to be:
Surf
Psychic
Recover
Calm Mind

thx to all