Baddies, or Bad Guys, is a generic term for enemies in games.
The word comes from the phrase "Take that, Baddies!".
A baddie is generally recognized by the fact that they are/have
- Bigger than you
- Better armed than you
- More hitpoints/mana/armor than you
- Faster than you
- A lot more numerous than you
- Often shooting in your general direction (unless they are Dysfunction in which case he could also be a goodie)
and quite possibly
- smarter than you
In the case of a game like say, Ninja Gaiden, all of the above apply. In a game like Battlefield 2, some apply, but the game is either going to crash or you're going to get kicked by the master server and/or PunkBuster for reasons often unknown (but absolutely no fault of EA's. nope, not their fault at all, oh no sirree)