As much as the problems with this game go way beyond the roster, I still want to share what I would have done differently. In an ideal world this game would have lasted way longer, so think of it less as "cutting" characters, moreso delaying them.
Gandalf -> Wicked Witch. This one is probably cheating, but I don't care. Gandalf was probably done before they cut him, so by swapping him out for somebody else we basically get an extra fighter for free! The Wicked Witch totally deserved to be added, and since this is long before Wicked that shouldn't be an issue)
Reindog -> Maxwell (Scribblenauts). I don't hate Reindog or anything, but he's the easiest cut because nobody would know he existed if not for this game. As for Maxwell - I loved Scribblenauts as a kid. He's my pure bias pick.
Taz -> Daffy. I don't really care about the Looney Tunes, and even I think Daffy was robbed. Taz can wait.
Garnet -> Samurai Jack. Garnet's the first of a few swap-outs where I'm getting rid of one of two characters from one series to get another series in. It hurts to cut a Steven Universe character, but I really doubt it deserves two characters on a ~35 character roster. I remember the biggest roster critique at launch was the lack of legacy CN representation, I think moving Jack up should help with that.
Morty -> Sub-Zero (I think part of why interest cratered for beta S1 was the doubling up on characters per series. Morty deserves to be added, but he can wait a while. Mortal Kombat, on the other hand, is one of the biggest gaps on the roster)
Stripe -> Fred Flintstone Two Gremlins so early into the game's life was a baffling choice in retrospect. I was planning on cutting Gizmo and keeping Stripe, but with the other characters being added this season being fairly dark (Rick, Sub-Zero, Black Adam) I think the contrast works in Gizmo's favor. Fred isn't all that exciting an inclusion, but he should have probably shown up by now.
Marvin -> Immortan Joe (Mad Max). Nothing against Marvin, I just really think there should be a Mad Max character and he was the most cuttable character. I'm stealing the idea from Gaming Gryffindor's/Capybara's video, Immortan Joe would probably have a more interesting move set than Max or Furiosa.
Banana Guard -> Brak (Space Ghost). I had no idea what to do with Banana Guard. On one hand, it's ****ing Banana Guard, but on the other he was explicitly a low-effort inclusion; swapping him out for someone like Ben 10 felt disingenuous. I genuinely contemplated keeping him because I couldn't think of anything better. In the end, I decided to swap him out for a Space Ghost character, with the "gimmick" (cost cutting measure) of incredibly choppy animations. Space Ghost himself felt a bit redundant with all the DC superheroes, and the mantis character's voice actor passed away, so Brak was the next character in line.
Agent Smith -> Agent Smith with a slightly more interesting moveset
Samurai Jack -> Mordecai. Because I added Jack early, someone needs to take his spot here. Mordecai's a top request, we know he was being worked on, not much to say.
Nubia -> Chani (Dune). I don't hate Nubia as much as a lot of people do, but it's hard to argue the slot couldn't be better spent. Dune, on the other hand, is one of Warner's biggest movie properties this decade and totally deserves a slot (don't think about Legendary Pictures they don't matter). Why Chani instead of Paul? I cut Garnet, I cut Nubia, and (spoiler) I'm going to cut Marceline - I accidentally cut a massive chunk of the POC, and I feel pretty bad about that.
Marceline -> Gumball. Marcy isn't a bad inclusion, but AT shouldn't have three characters when every other CN series on the roster only has 1. The Amazing World of Gumball is probably the most important CN series yet to be added here, so Gumball gets the slot.
Lola -> Taz/Marvin. Nothing against Lola, but she's somewhat derivative of Lebron - I'd rather bring back one of the other Looney Tunes. I don't really have a preference between the two, so pretend I went with the one you prefer.