Should I train my Raichu in this manor.?

Which manor are you referring to? If you are referring to the Old Chateau, I would suggest you move from there because the Old Chateau is where I go to EV train a Pokemon's Special Attack. If you want to train its' Attack stat, I would suggest you train against Machop or other similar Pokemon because they give EVs to Attack. Make sure that you feed it as many Proteins as you can feed it so that you max out its' base Attack to help give you the highest possible Attack for it.

I would prefer that you teach your Raichu Slam because while dig is a useful move, Slam is more useful with your Raichu's current setup because it will allow it to hit more Pokemon than if you taught it Dig. Plus, if you give it Slam, it can attack twice in the same time that it takes it to attack once with Dig. Just some thoughts.

Hope this helps :)

I prefer dig, slam only has a few extra damage points and it's not super effective against anything and has a relatively low accuracy. Although dig takes two turns I still like it more.

Slam.