According to Bulbapedia, no methods of IV evaluation exist before Pokemon Emerald. This was because developers initially aimed to make the Pokemon seem as realistic as possible, rather than as products of numeracy and mathematics. This aim is firmly established in Gen I with the absence of an IV judge, but this aim has become less of a priority as gamers have discovered the presence of IVs and EVs over time.
The only way you could find out a Pokemon's IVs is through the use of the equation presented in the above link.
Hope I helped. :)