it's obviously better to battle IRL, but online, it's
a) Fairer
b) More varied and challenging.
a) Online, everyone starts with teh same thing. The team of their dreams. It's no longer a battle of "Who is the bigger loser with more time to train", but more strategic. Everyone is given the highest standard of pokemon, so no one edges out the other with gameshark and such, no one edges the other because he/she has no life and spends 1000000 hours training, etc.
b) If you're living in say, Brazil, you'd be playing whom, your next door neighbours who don't know why tackle sucks, a few occassional opponents at the local card shop, etc. You'd be pitted against EVERYONE in the world who has the opportunity to get online. No matter where you are, you can battle against people from US, Canada, Spain, China, Brazil, Australia, etc. That's the real test. It's no longer "I am the king of the remote village Asdrioahstkhsdt in the remote region of Siheibwrleg", it's to prove to the world your real skills in pokemon.
And as much as I like how you prefer to imitate Ash, pokemon isn't real. Just like Neopet owners shouldn't feel depressed if their pet goes into a state of extreme hunger either. Honestly, in this forum, pokemon isn't Yugioh. No one here should believe in the "heart of the cards" (or in this case pokemon) because frankly, they're just bits on a gameboy catridge or PC.