>

He's not very funny but the fact he loses every fight by a dramatic margin and at the end decides to roast Reiner is beyond me and I just have to laugh at him for that.
you do realize he also almost eats Eren at one point right, quite frankly of most of the titans he gets closest to finishing eren of,  only the swift cut of one of his jaw muscles saved him (which shouldn't have stopped him eating since a jaw has muscles on both sides) >

Indeed that was close but what else would we expect from a titan whose name is dubbed the "jaw" titan and he sneaks up on Eren behind his back? Honestly, the fact that he wasn't successful in eating Eren really just proves my point of how incompetent he is. If your jaw is already on your enemy's neck, why would you wait to bite down? A competent jaw titan would have been able to bite Erens neck the moment he made contact, and the fact that Galliard didn't do that really proves to me that he is just a joke. And right after the sneak attack, in the real fight face to face, he proceeds to act as Erens punching bag. >


I say this because Galliard gets beat up in every fight without fail,

Many of them weren't comedic however.
Clearly someone needed to take over the Jaw Titan from Ymir, and Porco's primary role as a character was that, and the first thing that was introduced about him as a character was his strained professional relationship with Reiner, whom he does not consider worthy of the Amored Titan.
Furthermore, he serves an initial important role as one of the few warriors who never set foot on Paradis and experiences the determination of the scouts first hand. The Battle of Liberio was purposefully mostly set from the other side and Porco's perspective serves to show the normal protagonists look. He has never experienced mere mortal men charging at a titan headstrong to kill it. The scene that shows the fear in his eyes as he first hand experiences how galvanized the scouts are after having faced so much was very pivotal.

Galliard and the war hammer proceeds to get beat up by Eren,

No, the Warhammer initially beat Eren until the help of Mikasa, and Porco managed to land a sneak attack and was almost able to consume Eren and take the Founder if not for Levi's interference who cut his jaw muscles at the last moment.

This happens virtually every fight that Galliard is involved in

Actually no. Gallard has been involved in three fights: the first was against the mid-allied forces where he saved Reiner and was instrumental in achieving victory for Marley, the two battles with Paradis were hard-fought losses that were very close with both sides about to win at multiple points and most of the titans on both sides battered. >

Still a fact that the four titans lost against Eren and Galliard almost died to Eren, which was never the case for Reiner or Pieck, and yet Galliard still decides to roast Reiner before he dies. You also mentioned how Galliafd doesn't think Reiner deserves the titan, yet I've never seen him show anything that proves he is better than Reiner in any way. >


Still a fact that the four titans lost against Eren and Galliard almost died to Eren

Reiner also never beat Eren; it helps being the protagonist of the story to win.
They also would have beaten Eren if it weren't for the intervention of the other scouts. They didn't loose to Eren but to the combined efforts of Paradis, and of course Sieg at the time was a double agent so it was really three Titans against three.

which was never the case for Reiner or Pieck,

It certainly was, Reiner would have been extracted if he did not call for help to let the Colossus fall on them so they could escape with Eren. Reiner was also captured after a defeat to Eren and was only saved because the Cart Titan could spirit him away.

You also mentioned how Galliafd doesn't think Reiner deserves the titan, yet I've never seen him show anything that proves he is better than Reiner in any way.

Maybe not, but yours was a claim that the only purpose of his character was comic relief, clearly another purpose is to make Reiner feel inadequate and undeserving which has always been his issue. >

He was added for the drama with Reiner. He gets killed off when the drama's run its course. I don't really see how he could be comic relief because he's not very funny. He's also kind of just an antagonist for the Scouts to fight, like Pieck, who also doesn't have much characterization or versatility in the show's fights.