Seriously! I know it's to impress their boss, but I think that there is more to it than just that... I think they are lazy! Why do YOU think?
( :25: is now Team Rocket's!)

I've often wondered that too. It honestly couldn't be that hard to simply catch and raise their own. I guess Game Freak wanted to avoid any possibility of moral ambiguity for the antagonists. In G/S, admittedly, their plan is significantly more cruel.

I think that's only in the anime. In the games, Team Rocket's goal is generally to make money, and they do that via shady business with the game corner and trying to seize Silph Co. Stealing pokemon is just a way to make money, and they want to control mewtwo because it's insanely powerful. The anime made Team Rocket, well, Jessie and James.

Team Rocket's main figurehead goal is to collect every Pokemon by any means neccesary. They also deal in the illegal buying/selling/stealing of Pokemon. Giovanni, however, simply wants to collect the world's strongest Pokemon so he can rule the world. Hence, he begins researching Mew and creating the Mew clone known as Mewtwo. Red (or if you're a girl, Leaf, although it's Red in the game canon) defeats Giovanni, and he decides to retire and quit Team Rocket.

These motives are your simple average megalomaniacal mastermind plot. Most of the elements of Rocket is synonymous with the modern Mafia. You can see how later teams develop greatly from the Rocket's ways: Magma/Aqua try to (and succeed...terribly) at modifying the world using Pokemon. Team Galactic (or more specifically, Cyrus) wanted to destroy the world and rebuild it with their own rules.

Because they can't afford a handheld console and can't afford PokeBalls, so must instead, loan money to buy massive tanks and machines to steal others

If (anime) Team Rocket can't afford food, how can they build the hundreds of robots to try and capture Pikachu?

They can't afford food because they make 100 robots.

They arent always at loss of money, but when they have it, they blow it off on a lot of food. maybe their supplies is supplied by the HQ.

Jessie and James exist to provide comedic relief and episode-to-episode conflict. They are aware that they are in a TV show and can pull anything out of thin air to move the show along. They are continuously starving because it's funny.

I think the idea is to steal pokemon that aren't normally caught in the wild, ones that are powerful, or rare. Besides that I guess they do catch their own, to issue to grunts.

Simply, they just want to collect Pokemon for their boss in order to get better wages and positions.

Because Giovanni must doubt their ability to raise their own Pokemon. Perhaps they think it would be far easier to steal experienced trainers Pokemon because they have been through alot and considered the fact that taking them must be a whole lot easier than training their own.

Giovanni need pokemon to complete his evil task.

then Jessie James Meowth want to get bigger rank...

The Pokemon Black Market anyone?

~Chris

Make money, that is probably their primary objective. Why else would they have a game corner? Also, why hasn't Giovanni just kicked Jessie, James, and Meowth out of team rocket? Obviulsy they are not very good assets. The lowest of the grunts.

It's just so they can be comic releilf in my opinion.

Team Rocket is like the common gang. They will steal, make money at any cost. Capturing Pokemon is a ton more easier than stealing high leveled experienced trainer Pokemon and stealing these rare Pokemon results in money. I highly agree with most of these posts, outstanding views and Gio has to be a great villain of all of Pokemon history in my opinion. He knows when he has met his match and doesn't push his luck like Archie and Maxie, if you've been beaten at least twice/three times just quit , unless you're Red/Leaf/Gold/Kris/Ruby/Sapphire/Diamond/Pearl/Platinum lol.