Wobbuffet- The Patient Pokemon
Gold
 It hates light and shock. If attacked, it inflates its body to pump up its counter strike.
Silver
 To keep its pitch-black tail hidden, it lives quietly in the darkness. It is never first to attack.
Crystal
 In order to conceal its black tail, it lives in a dark cave and only moves about at night.
Ruby
 If two or more WOBBUFFET meet, they will turn competitive and try to outdo each other's endurance. However, they may try to see which one can endure the longest without food. TRAINERS need to beware of this habit.
Sapphire
 WOBBUFFET does nothing but endure attacks - it won't attack on its own. However, it won't endure an attack on its tail. When that happens, the POKéMON will try to take the foe with it using DESTINY BOND.

Location
Gold/Silver
 Dark Cave- Route 45 Entrance
Crystal
 Dark Cave- Route 45 Entrance (Night Only)
Ruby/Sapphire
 Safari Zone- SE and SW Quadrants; Evolve from Wynaut at L15

Moveset
Counter
 Mirror Coat
 Encore
 Safeguard/Destiny Bond

Item
Leftovers

Ability
Shadow Tag

Moveset Explanation
     Wobbuffet doesn't have much choice of moves. In GSC, it was hard to tell if a Pokemon was going to use Special or Physical attacks, so you didn't know whether to use Counter or Mirror Coat. Now in RS you can get a Wobby with Encore by evolving a Wynaut. This, plus Shadow Tag, makes Wobbuffet a great Pokemon to use. The last slot is your choice, but I'd recommend Safeguard to protect against poison and the other nasty status conditions.

     And, fun fact here, Wobbuffet is not my favorite Pokemon. It's my second favorite. It was my favorite until RS came along and I met my best buddy Blaziken ^_^.