What episode is this from? (gif included)

[Yash]

I've always wondered where this gif is from, it's somewhat of a 4chan meme:

 

[Hyatt]

It's in the episode when Brock gets Bonsly/Usohachi. The ninja school episode, dont know the dub names anymore.
Battle Frontier

 

[RapidPotential]

The episode's title is "From Cradle to Save". I actually recorded that episode onto my DVD recorder, so I remember it clearly.

 

[Casual_Furi]

http://pokealuealue.ytmnd.com/

FTW!

 

[Trainer Rachel]

http://pokealuealue.ytmnd.com/

FTW!

That IS pure win!! XD

 

[Blackjack Gabbiani]

Oh Pokemopolis, they refer to that as "BALEEEEEN WHALE".