Who are the villains at the end of the 90s X-Men cartoon intro?

Question

At the end of the 90s X-Men animated series intro, there is a clash between the Professor Xavier's X-Men and Magneto's team. I recognize most of the villains, but am unable to identify a few of them.

Who are they, and did they appear in the series at all?

I have numbered them below according the the screenshot.

1. Magneto
2. Juggernaut
3. ?
4. ?
5. Pyro
6. Mystique
7. Sabertooth
8. ?

Answer 1

1. Magneto - first appearance: One Man's Worth (pt 1)
2. Juggernaut - first appearance: The Unstoppable Juggernaut
3. Warpath - first appearance: Slave Island
4. Yuri Topolov - first appearance: Slave Island
5. Pyro - first appearance: Slave Island
6. Mystique - first appearance: Slave Island
7. Sabretooth - first appearance: Night of the Sentinels
8. Avalanch - first appearance: Slave Island