@Flufux  
I do agree that they should have introduced him earlier on in in the show, or should have at least referenced him much earlier on. At first I downright despised the plot twist, but after looking back at it, I can see why the writers did it. Grogar never encountered the Mane 6 before, unlike Tirek, Chrysalis, and Cozy Glow who all have past encounters with them and a reason to be out for revenge. And even if we didn’t get to see him for real, it leaves room for fans to speculate and make fanfictions about what the real Grogar was like in history and his epic battle against Gusty the Great. I can only hope that they’ll use him for real in G5, or maybe even bring back other old villains from G1 that never made it into G4, such as King Charlatan or the Raptorians.

@Background Pony #A790  
Maybe in the season 10 comics.
 
Personally, I would have liked to see Grogar in the flesh, but I also really didn’t want him to overshadow the evil trio who I think had a lot more personality than he did. If it was up to me, Grogar would have showed up a lot sooner than he did and join up with the alliance later so that the conflict between him and the Mane Six would feel a lot more personal.
 
Heck, even if he had to make his first appearance in season 9, then he could have been the main antagonist for the premiere and basically do everything Sombra did, and then when he’s defeated, he summons the other villains and forms his legion of doom, and if he leads them in the end, that position would feel a bit more earned, and if the other villains betrayed him, well…at least then we’d have at least one two parter with him as the main threat in it.

@Flufux  
I’m still not a big fan of the fact that they brought him into G4 only to cuck him for a plot twist that no one asked for. Hopefully he’ll get a real appearance in the future of the franchise someday.

Grogar: Ill have you know that I have a lawyer that could sew your ass, if you wont let me do my stuff for these people, because thats why you sent me into this studio, Im the one what they wanted most in “season 9”!
 
Jim Miller: ooh i would make you the main villain, but its against the rules when I write for y’all so called “all-powahful villains”
 
(smokes cigar with a smug troll grin)

@Background Pony #3BFE  
Yeah, sorry, but for the final battle we need someone with a personal rivalry with the heroes and well…an actual personality, but don’t worry, because you’ll be providing a magic bell for those villain’s to use, and someone will come along dressed as you to at least give the fans a canon G4 design for them to use. Does that sound good, mr Grogar, because it’s all I can do for you right now?
 
Grogar: Are you for real?!
 
Well it’s that or we can have you be tricked by a tape recorder again.
 
Grogar: Aw…fine, grumble grumble, but at least throw in some hints that I might show up in the comics or something.
 
Uh…sure, we’ll take that into consideration.