useing the moded gen II catch rate might help
The modified catch rate a is calculated in Generation III as follows:
Where
HPmax is the number of hit points the Pokémon has at full health,
HPcurrent is the number of hit points the Pokémon has at the moment,
rate is the catch rate of the Pokémon (which may have been previously modified from the use of the Heavy Ball or Safari Zone modifiers),
bonusball is the multiplier for the Poké Ball used, and
bonusstatus is the multiplier for any status ailment the Pokémon has (2 for sleep and freeze, 1.5 for paralyze, poison and burn, and 1 otherwise).
Given this formula, the maximum value for a (if the Pokémon could have 0 HP) would be catch rate × bonusball × bonusstatus. The minimum value for a (for a Pokémon with full health) would be ⅓ × catch rate.
if you can deciper the techincinal aspecets it may help also save before you fight it and just try,try,try again