To max out Mewtwo's Special Attack, you just need to give it the vitamin that raises Special Stat Experience (should be Calcium since Zinc wasn't introduced until Gen III) and then fight tons of Pokemon (of course, you will max out your Special Stat Experience faster if you fight Pokemon with high base Special Attack). Your Special Attack Stat Experience should always equal your Special Defense Stat Experience because of this (they did this to retain compatibility with Gen I).
If your Mewtwo defeats a Gastly in GSC, it will gain 100 Stat Experience in Special Attack and 100 in Special Defense as well. For instance, Gastly has base 100 Special Attack. I was just reading on another website* that the base Special Attack stat of the defeated Pokemon is used to determine the amount of Stat Experience your Pokemon gains in its Special stats. Special Attack and Special Defense share the same Stat Experience "EV".
So, if you want to "EV train" in Crystal, give your Pokemon vitamins and then go fight a bunch of Pokemon. (You should be able to look up more information about Stat Experience on your own if you're still confused). I would link to it - that article also explains Stat Experience - but I'm using my 3DS right now so I can't. I don't remember what the max amount of Stat Experience is, but there is an article on Bulbapedia with it. There's no way to check how much Stat Experience you have, so you'll have to keep track. It doesn't really matter which Pokemon you fight since every Pokemon contributes Stat Experience to each stat and there's no 510 EV limit to worry about. All you really have to do to max out your Stat Experience is just battle a lot of Pokemon. You can get enough Stat Experience to do this. Using vitamins will also give your Pokemon Stat Experience for a certain stat.Īnd yes, it is true that you can max out all your stats in Gens I and II. I believe that every time you beat a Pokemon, you gain Stat Experience based on the defeated Pokemon's base stats so if you defeated a Mew, your Pokemon would gain 100 Stat Experience in each of its stats since Mew's stats are all base 100 (I'm 99% sure this is how it worked). Sorry if all of that was unclear, here’s a much more cohesive guide.In GSC and RBY, Pokemon had what was known as Stat Experience, which functioned similar to EVs. Only other thing to mention is you can’t breed two Pokemon with the same stats together so you can’t interbreed to do this. The female ekans breeds with a Male ekans giving me a Male ekans that whole not shiny has the stats needed to pass that quality on, breeding the ekans with a female Eevee eventually gave me a female eevee with the needed starts and then finally breeding that female eevee with a random Male one gave me my shiny Eevee (odds were 1/64) I caught the red Gyarados (Male is easier for this) and bred it with a female ekans a Pokemon in both Gyarados and eevee’a egg group, in gen 2 the opposite gender interest the stats of that parent. Finally got around to this and have to say it felt good, in generation 2 Pokemon shininess is decided by the values of the Pokemon’s stats, stats which can also be passed onto others by breeding, if anyone wants the specifics I can go into them but essentially it went like this,