Level One Playthrough

[Zidane77]

Well it's at least worth a try, have any idea where that can be inflicted on disc 2?

[Xithor]

Well it's at least worth a try, have any idea where that can be inflicted on disc 2?

I used virus when I was leveling up Dragon's Crest and that was on disc 3 when I had the Golden Chocobo and was able to fly to Vile Island and face the Yans. They can wipe out the whole party so it was difficult. The only other thing that would work is getting Zombie on your party which can be done in the Iifa Tree or from that Zombie Whale on the shores of the Forgotten Continent.

[Zidane77]

I used virus when I was leveling up Dragon's Crest and that was on disc 3 when I had the Golden Chocobo and was able to fly to Vile Island and face the Yans. They can wipe out the whole party so it was difficult. The only other thing that would work is getting Zombie on your party which can be done in the Iifa Tree or from that Zombie Whale on the shores of the Forgotten Continent.

According to this (The FAQ section at bottom), it's impossible to go through the forced pandemonium fights without getting EXP.
GameFAQs: Final Fantasy IX (PS) Low-Level FAQ/Walkthrough by KADFC

You get healed before the battle and for some reason it heals any status effect you might have (including zombie,virus etc.)
So feel free to try it if you want though, but against Tantarian it's worth a shot.