Knock Off>X-Scissor on Scizor. Bug's kinda a crappy offensive type most of the time. Knock Off still hits Psychics super effectively, isn't resisted by Fire (and those'll be trying to switch in on Scizor a lot), and has the incredibly useful effect of removing the opposing poke's item (bar a few exceptions). Bullet Punch after a Swords Dance is what's gonna do most of the work anyway.
I don't think I can get knock off in pokemon x, it says on the wiki by move tutor but I went to every move tutor in the game and they don't teach it to me.
As for the kabutops and Therian Tornadus I think I would like a kabutops. I kind of stray away from legendaries as I don't really like them, except for Mew because of the 1st movie. Kabutops though sounds awesome, it looks like I will have to try and get one through trading though as pokemon x can't get the right fossil... there are so many hurdles in breeding haha.
And as for stealth rock, is there any other suggestions over Mamoswine? I'm not a fan of him really.
Also, with my mons having wrong moves and abilities, that's all unintentional, I did want a pixilate Sylveon but I was breeding for so long when I finally got the right IV's I just took what I had haha... and with lotad I didn't realise giga drain was an egg move in my game. If I ever get the motivation to rebreed them I will as I have a 6IV ditto it isn't that bad anymore (it was awful at the start).
I'm happy to correct the EV spread though, whenever I come across another reset bag in super training I guess haha... haven't seen one in a long time.
Edit: I really like my mega scizor, I don't really want to change him for mega altaria, that isn't to say I wont change him for a different mega if I like it though.