I felt the need to chime in on Mega Lucario.
Extremespeed is a big deal. 95 base speed is - to be blunt - pretty slow in a metagame which is full of fast offensive pokemon that could potentially one-shot it (E.g. Terrakion, Keldeo, Thundurus-T, Latios, Latias, Salamence, Starmie, Alakazam, Jolteon, Gengar...)
It's a pretty big list, and no matter how powerful Adaptability Close Combat is, it won't make any difference in the world if Mega Luc can't even get the attack off, because it gets killed by Keldeo's Secret Sword first. Or something.
But Lucario does get Extremespeed, and at +2, it can sweep through a weakened team quite nicely. Of course Mega Luc's Espeed will likely be a bit weaker, which is a bit of a nuisance (though in all fairness, it remains to be seen weather it is significantly weaker, so as to miss KO's). Of course, Mega Luc does get Adaptability Bullet Punch - but honestly, Normal is probably a better typing offensively than Steel. For example, the aforementioned Keldeo (as well as Thundurus-T and Starmie) really screw over Mega Lucario with Bullet Punch> Espeed. Then again, you do beat Terrakion and Gengar, I suppose.
So, if that confusing paragraph told you anything, it's probably that the general lack of information makes it hard to guess what pokes are going to be like with any kind of accuracy. What I can say about Lucario though, is that:
1. Extremespeed is a very significant move for a base 95 speed, frail sweeper;
2. If said Extremespeed is weakened too much for Mega Lucario, then it could hurt his effectiveness.
3. All of which, however, could be remedied if Mega Lucario got a boost to it's speed. With base 110, it could outspeed the majority of what it needs to, and abuse it's obscenely powerful Close Combat to the fullest.
Also, what is this nonsense about 'If Mega Lucario gains speed, it will be worse, because Terrakion'. What I don't even.
A stat boost is... a stat boost. How can that be bad... Ever?