Special illustration cards seem to replace one of the two reverse-foil cards rather than the rare or holo-rare slot, so you could get lucky and get a special illustration Pokmon ex and a full art Pokmon ex in a single pack (I think?), but the odds would be pretty small, and thats only because the special illustration card replaces a different foil-style card of the 3 foil-style cards
In a planeswalker-heavy build, that means walkers enter with twice their loyalty, often letting you ultimate them the moment they hit the battlefield
The Marauding Raptor ability will trigger, dealing damage to the Polyraptor, which will in turn create another token of it again and again to essentially create infinite Polyraptors and deal endless damage to your opponents with Impact Tremors
Unfortunately, you wont be able to change the Trainer Card picture in any way
GX Variants As you may be able to guess, GX cards are very similar to EX cards