Love it. You're a saint and a scholar for working on this.
I love what you've made so far, and I've got plenty of concepts if you want them. I'll suggest a couple new things but make sure it also utilizes what you've already made. I don't know how hard it is to rip audio from Pocket Mortys, but I'll look into that today for you. Additionally, if you're looking for complex helper code, I think Vanguard Princess characters may have plenty for you to work with.
Assuming a "Morty gauge", where Morty can help if it's full (and yells at Rick after he gets utilized or gets congratulated by Rick):
- Blocking by Holding Morty, where Rick takes no damage, even from Hypers.
- Pushing Morty forward at the enemy, knocking both of them off their feet while Rick has an opening.
- Morty summons Fart, who sings the Goodbye Moonmen song, paralyzing the enemy. (source in S02E02)
- Morty pulls out Rick's toolbox and throws a ton of debris at the enemy, keeping them in vulnerable (but weak) combo recoil while Rick is free to attack.
General Special Possibilities:
- With the Meseeks box, you could have him call in a AI helper Meseeks that stays until it takes one hit, like the code of the Queen Xenomorph calling in drones as backup.
- Healing a modest amount via drinking before throwing the glass bottle as a projectile.
- Rick engages his stone age armor, which can take a few hits before breaking (code from the AVP Colonial Marine Private might come in handy).
- Rick fires his particle beam wristwatch and releases a snake from his snake holster, which turns back into the enemy after a couple seconds (concept in S02E04; code can be taken from Anakaris of Darkstalkers).
- Spamming the Meseeks Box until he creates a firing squad (the last one to attack doesn't have a gun and just throws a wrench or random debris)
- Calling in a stampede of variant Mortys from Pocket Mortys
- Summoning Squanchy, who morphs into Mega Squanchy for an attack burst (you could use the Servbot hyper code from Tron Bonne and have the player assume control of Squanchy)
- Calling his Power Armor from the Purge (maybe the best way to do it is to create the beacon, which summons the platform after several seconds; during this time, Rick is still vulnerable to attack but the beacon cannot be destroyed. After engaging the armor, Rick has no recoil, boss armor, and deadly attacks.)
- Rick and Morty step out of a portal and look around nervously. "Holy shit, we're in a game, Morty!" "Ah, geez, Rick." (may have to source; not sure where to get it)
- Rick reloads his laser gun and puts it in his back pocket. "Looking to get purged?" (quote in S02E09)
- Rick lands his spaceship and falls out drunk, surrounded by glass bottles. The spaceship is static and stays in the background for the round.
-Rick pulls out his whiteboard covered in formulas. "You're a piece of shit, and I can prove it mathematically." (quote in S02E01)
- Rick walks over and spits on the defeated character. "School's out, bitch." Morty looks concerned. "Ah, geez, Rick." (quote in S02E06)
- Unity walks over and flanks Rick on Both sides. As they get risque, Morty looks incredibly uncomfortable and walks away. (Unity/Rick quotes in S02E03)
- Rick and Morty high-five and comment before walking into a portal and disappearing. "The Rickest Rick and the Mortyiest Morty." "Hahahah, yeah Rick!" (quote in S01E10)
- The screen flashes white and Rick is in an apron, grilling, while he and Morty are surrounded by the memory parasites. Rick yells "I'm Tom Cruise in 'Cuisine'!" before looking around and saying, "Ahh, shit." (quotes in S02E04)
- Rick and Morty celebrate as Rick gives the entire monologue of S01E01, "Rick and Morty forever.com" etc, even going so far as to break the fourth wall and hold the sides of the screen as he gives the end of the rant.
- Grunts from the Council of Ricks come in from a portal and thank the enemy for apprehending Rick C-137. They grab Morty as well.
- Jerry walks over from offscreen and asks Rick if he's seen the batteries to the remote/ if he can open a jar. Jerry looks up at the enemy and casually says, "Oh, hello!"
- Mr. Goldenfold walks over and screams at Morty to get back to math class. He panics and runs past him.