1.Stats: Should Sharpedo get a stat boost, Evolution, Mega Evolution or nothing?
+80 BST can be granted.
An evolution would have been good, but now we might be forced to have a side evolution at best.
A Mega already exists, another one can work.
2.Should Sharpedo get more abilities?
Swift Swim or Water Veil would be good. Defiant and Moxie would be good, so would Gluttony and Inner Focus.
3.Should Sharpedo get more moves?
Sucker Punch would be good. Assurance, Beat Up, Trump Card, Aurora Beam, Special Poison-type moves like Sludge, Sludge Bomb, Sludge Wave can be given. Psybeam, Psychic and Psyshock can also be given. Nasty Plot would be very good as well, alongside Swords Dance.
4.What additional typing Sharpedo can have?
Ice, Steel and Normal can be granted. Poison and Psychic are also options.