I love psychic types becuase they tend to fit in to my battle style hit hard hit first hit fast due to they're high speed and high special attack
espeon like ohio side but you can pop in mewtwo if you want a legendary so if you need help with any other pokemon let me know
Get espeon. He has good all around stats.
To answer your exact criteria, you want an Alakazam, he has the highest Sp Atk in the game for a non-legendary, and great speed too. The problem is Alakazam has really bad defense so Crunch will certainly KO him, as will most Physical moves.