In Pokemon Red and Blue, Lapras is received as a gift from a Silph Co. employee, making it an extremely rare creature to obtain.
Once added to the Pokedex, though, Lapras can become a focal point of any team. As one of the rarest in Generation I, the Water/Ice-type is incredibly powerful.
Late in the game, it can be a valuable Pokemon to have against the strong trainers in the Elite Four. In fact, if trained well enough, it may be able to take out Lance's Dragon-type team all by itself.
Note: This article is subjective and reflects the opinion of the writer.
The best moveset for Lapras in Pokemon Red and Blue
While Ice Beam is a good move, the power to accuracy difference between it and Blizzard makes Blizzard a better choice. Blizzard does insane Ice-type damage and has a 10% chance of freezing the opposing Pokemon. Blizzard is arguably the best Ice-type move in all of Pokemon.
Thunderbolt is an incredible, 100% accuracy Electric-type move. This gives Lapras a leg up over Pokemon that would normally resist. Throwing a Water-type versus other Water-types isn't the typical plan. With Thunderbolt, this will allow Lapras to take care of them with ease. Not to mention, it has a 10% chance to paralyze.
Surf will give it a STAB much like Blizzard. It is a very strong Water-type attack and doubles as an HM. Riding on the back of Lapras is what Pokemon is all about. Lapras can use Surf to devastate many opposing Pokemon, especially Bruno's Onix duo in the Elite Four.
Sing is a great status move that should be utilized all throughout the Generation I Pokemon games. Pokemon Red and Blue is one of the most difficult series of games and having a Lapras can ease the pain. Putting an opposing Pokemon asleep with Sing allows Lapras to run through them with its other moves while they are in their slumber.