How do I increase its stats?
Sp. Atk- 126
Sp. Def- 169
Should I make any changes to this as well?
Right, Buy loads of Proteins irons and every other stat changing item (as Mew :3) said these are available at Shopping Mall 9 on route 9. When you have fully pumped up all your stats with the items from the mall. Then when you have done this you start EV's training for attack and maybe a bit of speed.
Pokemon for Attack EV's
Pokemon for Speed EV's
Beat any of these Pokemon that are above and you will gain an EV.
Now here is the moveset I would suggest.
This set is brilliant for sweeping if you give you Scizor a Life Orb (obtainable at the Gear Station). This will boost attack even more. Bullet Punch is the main sweeping move you can power-up with Sword-Dance if you like or you can go straight out and hit hard with Bullet Punch which is powered up by Technician and the life Orb.
Hope this helps. :)
You can use Protein to increase you attack by 10 EVs. With Scizor, it's important to have lots of Attack.
Also, try this moveset: