If you mean species as in type, then first of all get a list of all the types and find the one with the highest base stat. for example blissey. its a normal type and has 255 base hp. then ev train it by killing heaps of Pokemon that yeild hp evs like stunfisk. stunfisk gives 2 evs and with the power wieght will give a total of 6 evs

keep track of your evs becuase you cant find out any other way

hope I helped