I'll probably make a book where I give my opinion on ships from numerous fandoms. Actually, yeah, I'll do that.

~Reasoning behind placements~

Alphyne (I don't know how the ship name is spelled): Let's go lesbians. Tbh I think this is the only Undertale ship that I ship on a regular daily basis. They're just so perfect for each other?? Plus it's the nerdy shy person x athletic outgoing dynamic?? Tbh that dynamic is one of my guilty pleasures. Plus, it's canon so that's a bonus right there!

Errorink: I don't really have any justification for this one, and NO I DID NOT JUMP ON THE BANDWAGON. According to the wiki, people ship it because of the whole "opposites attract" dynamic but I feel like that isn't the case. I just feel like there's so many possibilities for them and, out of everyone in the Multiverse, Ink would be the best person for Error. I just..... AAAAAAAAAAAAAAA MY OTP.

Afterdeath: Yes. Just yes. No reasoning or explanation needed. Just yes.

Kustard: I was gonna put this in OTP, as it is one of my favorite ships, but I didn't put it in OTP because I won't be like "No that's wrong" if I see you ship them with someone else. Not that I have a problem with people shipping other ships, but it's like a "if you don't have this ship in it, you lost my interest" thing?

Sansby: This ship is actually super cute. It was one of my first ships for the Undertale fandom, and even now I still ship it despite it not being like one of my main ships. It's like that "this customer keeps coming back and talking to me the whole time they're here" dynamic. Especially in the context of Underfell.

Cream: This is the Dream and Cross ship I personally prefer. I just didn't put it in OTP because I don't get that inner shipper feeling when I see something doesn't have Cream in it, ya know? It's hard to explain. Do I think that other Cross and Dream ships are cute? Ofc. Do I sometimes ship them with other people? Yes, I admit to that.

Crossmare: As I said above, I think other ships are cute too! I don't personally ship this, but I've seen so much fanart for it that's really cute!

Grilfet: I don't really see any problem with this ship. I think it's a little underrated, and I don't really have any restrictions or certain requirements when it comes to this ship.

Paperfresh: It's cute! It's also funny in a lot of contexts because Error absolutely despises Fresh, and then his son ends up dating him.

Chasriel: This ship is super cute too! Since they're siblings through adoption, it doesn't necessarily count as incest, right? Or does it still count as incest? I don't know. But I do think it's super cute!

Frans: I personally do ship this, but I have a lot of restrictions and requirements for it. If it's just fluffy best friend shipping, then anything is fine. But if it's a romantic shipping and NSFW, then it definitely must be legal (Frisk must be over 18 years old). There also has to be some context on how they started dating and doing that. But generally speaking it's a cute ship!

Charisk: This is more of a crack ship in my opinion, but since there wasn't a category for that I put it in that category. It's cute! I don't know if it technically counts as necrophilia, since Chara is a spirit.

Papyrisk: Ehh..... I don't really like this ship. But since Frisk did go on a date with Papyrus in the actual game, it's not too too terrible.

Redberry: This ship is cute, though I don't really ship it. It's not a terrible ship, there's definitely much worse out there.

Torigore: I mean they were together at some point and did have a son, but it definitely depends on the time and context. If its before the game, like when Asriel and Chara were alive, then it's good! But if it's during the game or even directly after, I'm a bit iffy on it. It's not a horrible ship, there's a lot of potential for it! But, I don't necessarily ship it.

Errorberry: I... don't ship this or really like it for that matter, but it's not unbearable. It has some cute fanart too. It's not a terrible ship with no logic behind it.

Soriel: I don't really ship this either, but I do think it's cute! It has a lot of potential as well.

Papydyne: Ehh..... it's not ungodly or anything, but I don't really ship it. In my eyes, they're much better as friends.

Asrisk: I couldn't really see the picture that good, but I think it's Asriel x Frisk. Again, I don't really ship it, but it's not a terrible ship!

Dreammare: I CAN EXPLAIN. So for this it all depends on the context, really. Mostly if they aren't biologically related. For example, I'll use Dreamswap as an example, the term "brother" is just used because they're like always together (at least prior to the apple incident) and they're like two sides of the same coin. I least I think that's how Onebizarrekai (the maker of Dreamswap) explained it. But yeah.

Errorfresh: I don't ship this and it doesn't really make any sense to me. I mean, does it have some potential? I guess. Is it cute? Eh.... just so I don't trigger people, I'll say yes, it can be.

Fontcest: Kill it with fire. Kill it with fucking fire.

Flans(?): Kill this with fire too. Burn it to ashes. Send it to the inferno.

~Honorable Mentions/Not Included Ships~

Dustberry: I don't know how this one wasn't included. But I would put this in either OTP or Love It. I honestly don't have any justification for shipping this, and I honestly don't know if I jumped onto the bandwagon or not with this one. But they go together for me, so it's alright.

Redlust: I personally do ship this, it's one of my guilty pleasures. I would put this in the Love It category. For me, personally, Lust is just a really flirty guy who is very outgoing, confident, and really good at advice when it comes to relationships and self-confidence. I have them as best friends in my main AU, but I wouldn't be against writing them as romantic partners.

Killermare: This is my personal favorite Nightmare ship, but I'm not opposed to others, as I stated with both Cream and Crossmare. I would put this with Cream in the Love It category for that exact reason, plus I'm not too crazy about the ship.

Inkmare: What is the context behind this? If the last three categories weren't so.... hateful I would've bunked it down. But depending on the context, I'm okay with it. In my opinion they aren't very compatible, but hey, you never know.

Horrorlust: This is one of the ships I mainly use in my AU. I'll admit I did kinda jump the bandwagon with this one.

Ink404: Ink x Error404. I ship it. Add it to Love It, since there isn't a category for crackships. This is my own personal crackship for Ink. I don't know how I started shipping this. I really don't.

Errorink404: A threesome/poly relationship between Error, Ink, and Error404. Add this one to Love It as well.

Asrigore: I saw this on another tier list in the pictures. Kill it with fucking fire, and send anyone who ships this to the deepest pits of Hell. Did them a new layer in it. Send this entire existence into the inferno. Don't talk to me if you ship this, Toriel x Asriel, Toriel x Frisk, Toriel x Chara, Asgore x Frisk, or Asgore x Chara.

Drink: Literally the only thing I can think of when it comes to this ship is "When you're sick of emotions and your friend doesn't have any". It's not a terrible ship, to me it has more logical reasoning behind it than Inkmare, so I'm gonna slap it into either the It's Okay category or the I'll Allow It category.

Inkberry: Ho ho ho this is cuteness. I don't ship it but it's cute. I'll put this in the same categories as Drink.

Friza: Frisk x Aliza! It definitely depends on the context. Like in my AU, it's Undertale/Classic!Frisk x Aliza, so they're the same age. But if it's in Horrortale only/specifically, then it's a big no no. My reasoning? Horrortale takes places years after the end of a Neutral ending. So Frisk is either dead from old age or is much much older, and Aliza is a child.

And that's all I got for right now.