Get ready for an animated musical that features all of your favorite things from the genre including: Songs that last 10 seconds, useless main characters, and a total lack of moral or lesson to be learned. Don Bluth presents Rooster Elvis & Sex Chicken: A Musical Love Story.
System Mastery 
You forgot the most iconic Don Bluth movie (at least in my mind): A Land Before Time, a.k.a. Bambi with dinosaurs except Bambi’s mom dies right at the beginning.
As much as you guys panned The Secret of NIMH, I actually really like it: I recall first seeing it as a kid and having that same reaction as those kids Jeff showed The Dark Crystal to (I think he mentioned this in a podcast wayyy back), basically “How the hell was this made?!” and it always fascinated me as a kid, and when I rewatched it as an adult it was still a lot better than most of the cartoon drek I watched as a child.
But yeah, Don Bluth is definitely one of those guys whose material got weirder towards the end of his career (I don’t think he’s actively working anymore, but correct me if I’m wrong). Like NIMH, A Land Before Time and An American Tail are all classic kids’ movies of the “scar your children for life” variety, All Dogs Go To Heaven is also a classic but already starting to get a little weird, and it all just goes downhill from there.
I kinda have to love the guy though: as much as I cried as a kid watching his movies he at least thought highly enough of kids that you could give them a serious narrative with some heavy emotional weight… as long as you puncutated it with some weirdness. Eventually he just seems to have started focusing more on the weirdness.
Jesus, all of those films I listed remind me of the fact that Don Bluth’s greatest legacy is the fact that all of his serious kids’ movies were either turned into predictable sequels churned out at a regular interval that were much more kid friendly (like with A Land Before Time) or spun off into more child-friendly sequels which were then adapted into Saturday Morning Cartoons (like An American Tail: Fievel Goes West). I think there’s a few more of his films which had sequels made for them which were pretty much the same as the first one except much more family friendly.
It’s also worth mentioning that Don Bluth was a character animator on Disney’s Robin Hood as well as a number of Disney films through the 1970s.
Also, Robert Altman is the director who had his actors talk over each other, and Chris Columbus only wrote the screenplay for The Goonies. (Richard Donner directed it.)
I’m going to need a good system to play as a Frog Bouncer in. Not a Slaad or anything like that, but an actual frog.
You could maybe be a Frog Bouncer in Golden Sky Stories but the tone’s kinda off from this movie.
Totally unsolicited answer to one of your questions: Chanticleer is the name of a rooster from a long tradition of allegorical animal fables which kicked around northern europe during the medieval period. The main character from those stories, Reynard the Fox, actually shows up in the Canterbury tales. Which makes this a weirdly obscure folklore/literature reference.
I adore Bluth, tbh…despite his catalog being very…spotty. His animation is spectacular. His hits are hits. His misses are…really bad, though.