He's so, so bad. His acting is wooden for CW standards and even though he's playing a character known for being fun and hyper charismatic, his performance is so flat and low-energy. And the worst part is when he tries to be "funny," it's physically painful.
You know who would've been excellent as Gar? Inaki Godoy, the dude who plays Luffy in One Piece. Now that's one energetic and charismatic motherfucker.
I couldn't agree more, everything you said is exactly how I felt about Gar / Ryan on Titans. That episode in Season 4 focused on him was such a painful grind to get through. Beast Boy didn't deserve an episode to himself on Titans - hell, he didn't deserve to be on the team. I always found myself hoping that the next episode would be the one that got rid of Gar for good, because that would be preferable to having Ryan still there.
And oh man, his humour. It's awful. I feel sorry for the Titans - because Gar seems like he'd be absolutely insufferable to be around.
Oh, I have seen that fan casting and I completely agree. I wish they could've re-cast Gar. If I was able to change one thing about the show, it would be that.
Also - as soon as this website allows me to DM you (I just set up my account), I hope you don't mind if I do - there's so much I need to get off my chest about him, and I feel like you get me!