So after hearing so much about Joey's amazing Rattata, I decided to test just how amazing Rattata is.
I started a new game on red version, got through the beginning section until I could buy pokeballs, immediately caught a Rattata, put my other pokemon away, and proceeded with the Joey's Rattata challenge.
I needed to grind a bit to get up to level 14 to learn hyper fang, but once I got that, I made short work of Brock.
Misty was easy too, and as it turns out, Rattata can learn her bubble beam tm, so now rock types will be a breeze.
On to visit Bill, wait a second now, Rattata is becoming a BAMF, he just took down all of nugget bridge, and everyone on the path to bill without needed to be healed!
On we go, beat the team rocket thief, ooh, Rattata can also learn dig. This is getting interesting.
Really Rattata, you just killed every pokemon in the st anne, including the rival's, with ease, without need to heal, I mean, who needs to heal when you kill everything in one hit. Time to start carrying a HM mule, it will not participate in any way other then strength surf fly and cut.
At this point, Rattata is such a beast, nothing can stand against him, I basically start speed running at this point, avoiding lots of battles, running from random battles, replaced hyper fang with body slam because it's slightly stronger and more accurate, replaced bubble beam with ice beam, still have dig, and learned thunderbolt.
So by the time I get to the Elite 4, Rattata is level 73. He tore through them like tissue paper.
Joey's Rattata challenge results; No challenge, Rattata is a BEAST!