Also is there a way to get back to santa village to catch more Shelders? The shelder I have has a bad nature for a defensive type, and I want to catch a different one.
On Dratini: You are doing everything right. Keep thrustin' that super rod in the lake area where the dragon claw tm is received. I had to come back twice looking for this Pokemon before I finally captured it, I don't know if it was overkill but I checked every tile like I did looking for feebas in Hoenen. Don't get discouraged-- dratini's there, mine is living proof. She has since grown into a dragonair named Sangrael. Until she finishes growing up Mithril my Kingdra is taking on most of the work load :)
On Shellder: As far as I am aware there is no way to get back to Santa Claus, but I know that is not the only place where shellder live so don't despair. Try the waters of Vermillion City, that is where I am pretty sure I've bumped into them. But others have gotten thenlm by fishing on the island during the "evolution solution" plotline with Slowbro.
On Ev training. For a special attack ev yield Lavender Town's Pokemon Tower is a place to start by battling the gastly and the ocassional haunter. Horsea also gives you 1 special ev pt and they're really common while fishing on Cinnabar Isand. Psyduck can also give you the special lift, I like to encounter them by swimming in the pool next to Viridian City Officer Jenny.
Another good hotspot with Oddish and gloom to boost your special attack is in the grassy area near the Pokemon center where the "mysterious garden" plotline happens. In the same grass you can fight bellsprout and weepinbell for a physical attack boost.
For more physical attack evs fight Nidorinos in the Pokemon reserve that marks the entrance to Fuschia City, you are bound to run into Scyther once in awhile if you do that often enough too. Growlithe is also available to fight in the imite house by the using sweet scent. And Gyarados is another option for attack ev, they pop up in many places, notably the waters blocked by Snorlax.
I hope some of this is helpful to you.
P.S I stole the eevee too. You are just going through stages if guilt, as far as I know keeping eevee does not interfere with any plot in-game. The only thing you would be rewarded with was Mikey's satisfaction... Personally I would rather have a Jolteon!