Why is Leech Life so weak in Gen 1-6?

Question

In gen 1-6, Leech Life's power was 20. In gen 7, they changed it to power 80. Why?

Answer 1

Because it was.

It was entirely Game Freak's decision to make it so weak. I believe it was intended as an early game move, to be replaced by something better as soon as possible.

A potential reason it was buffed:

Because it's called "Suck Blood" in Japanese, and that just sounds more menacing than a 20 BP move that stops doing meaningful damage after the first gym.

Source

Hope I helped!

Comments

Making the change also facilitated some new physical Bug types that were released in the same generation.  Both Araquanid and Golisopod are capable of using it to devastating effect.