Haven't seen the anime since Johto and this is obviously by no means official. However I figured it'd be fun/amusing to post it.

College Humor actually did an updated Pokérap that's actually equal parts serious attempt and poking fun at just how absurdly large the Pokédex has gotten over the years. You just can't help but laugh when this part comes up:

"GOTTA CATCH 'EM ALL! GOTTA CATCH 'EM ALL!"
"But I have a life......"
"LEAVE IT!"

Anyway enjoy!