The Creature from Black and White. I really think it's the best virtual pet. It's an intelligent little thing with it's own personality, and it's actions have significant consequences in the game. You can screw up by not raising it right.
I taught him to play catch and I gave him a teddy bear, which I never forgot to pack each time we switched worlds. I taught him to throw lightning and shit on houses(accident).
Sims. Not necessarily the pets sometimes, but you can do some goofy shit with a family of 6 cats Minecraft pets aren't very fun though :c I have started calling my dogs collectively as "Team Creeper Fodder", because you can't even name them individually, and half the dogs I ever have end up meeting their demise to - you guessed it, CREEPERS. I can never get enough cats, because as soon as I get one, they always disappear by glitches. I had the game crash on me once after I got a cat, and then the cat didn't appear when I reloaded the game. Pokemon was pretty fun, but I don't even play it anymore because I kinda got bored of the ds, computer games kinda took over :<