Meowth Uses Outside Help to Defeat Onix 

The Indigo League episode titled "Who Gets to Keep Togepi?" came out.

The main protagonists decide to host a tournament to determine who would become Togepi's trainer after the egg hatches. 

Team Rocket's Meowth throws his hat in the ring, but his first-round encounter is against Brock's Onix, a terrible matchup. 

Meowth has a brilliant idea after taking a Rock Throw to the face and noticing two buckets of water nearby.

Meowth throws buckets at Onix, weakening it enough for Fury Swipes to end it. Meowth wins despite cheating, shocking everyone. 

Despite losing the challenge, Misty owns Togepi because it imprinted on her first, hence Meowth's efforts were wasted.

Also See

A Hardheaded Battle of the Metapod