There are so many:
-Double Dare
-Doug
-Figure It Out
-Rugrats
-Alex Mack
-The Mystery Files of Shelby Woo (Nobody remembers this one though!)
-Are You Afraid of The Dark?
-Hey Arnold!
-Kenan & Kel
-Clarissa Explains It All
-Rocko's Modern Life
-GUTS
-Legends of The Hidden Temple
-All That (It got really bad when Jamie Lynn joined the cast though.)
-Pete & Pete
-Real Monsters
There's way too many, Nickelodeon was my favorite channel when I was younger
Rugrats (my absolute favorite)
Hey Arnold!
Doug
Rocko's Modern Life
Aaahh! Real Monsters
The Angry Beavers
CatDog
The Wild Thornberrys
Rocket Power (although it came out in August 1999 but bare with me here )
Kenan & Kel
All That
) Rugrats, GUTS, Legends of the Hidden Temple 
)