1.Stats: Should Gallade get a stat boost, Evolution, Mega Evolution or nothing?
Gallade can get +22 BST.
Gallade can get an alternate form.
Gallade can get a side Mega.
2.Should Gallade get more abilities?
Synchronize would be good. Hyper Cutter is also an option.
3.Should Gallade get more moves?
Play Rough can be given.
4.What additional typing Gallade can have?
Ghost, Electric and Fairy are options.