Moe = sprout (according to the Kanji 萌 used) but it is also slang for placing emphasis on the cuteness of the girls in anime.
It seems to be a parody of the game "Super Monkey Ball" more than anything else.
ownz = own
u = you

Piro speaks:
well, there are a few reasons i've been veering away from excessive l33tspeak. First off, if overused, it can be very cliche - there's nothing worse than a joke that is beat to death. Overuse on a regular basis can dilute jokes or situations where l33tspeak can be quite humorous.
Largo is and has been a character that has been hard to nail down since MT started - he's very hard to control, really. Writing is an organic process, and characters tend to wander in thier own directions. Considering largo's nature, it's like chasing dustballs on a windy day :P
For a long time people started to think largo was completely crazy, or stupid, or an idiot, or many things along those lines. The truth is, Largo is actually one of the smartest characters in Megatokyo. He's brilliant, but like a lot of brilliant minds, his thoughts manifest themselves in a lot of different ways.
Keep in mind that in MT, the characters do change and evolve. It's both a curse and a blessing, and I don't claim to really be in full control of it :P