It just had to be the route of Fate/stay night which has Saber calling Archer and Rin intimate, Archer putting his jacket around Rin to keep her warm, and a lot of other Subtext that also brings us Archer's Face–Heel Turn and Rin hooking up with Shirou.
The Ace Attorney games like to do this quite a lot. The guys at Capcom (or at least the writers/translators) like to shiptease all the popular pairings at the same time, without giving any solid backing to any of them.
"Thanks to you, I am saddled with unnecessary... feelings."
In 3-5, Phoenix is clearly concerned with Edgeworth's well-being, even when Maya is in a very dangerous situation. (The concern is very much mutual - Edgeworth charters a private jet to see Phoenix when he hears that Phoenix is in hospital.)
Then there's the fact Phoenix acted like a betrayed girlfriend when Edgeworth disappeared in Justice For All...
Also in Justice For All, Phoenix more or less admits that he's only surviving the extreme stress of case 2-4 because Edgeworth is on his side. He's also got a mid-trial revelation about how much he trusts Edgeworth, and after the trial you can express these feelings by giving Edgeworth Franziska's whip.
And speaking of the whip, Edgeworth then gives it back to Franziska in a post-credit scene that ship teases them. Edgeworth talks about them standing "side by side", and it's also the first time Franziska shows any emotion besides whipping rage. This scene also makes Phoenix sound a bit like Franziska's love rival. The ship tease runneth over - if you're not reading the relationship between Edgeworth and Franziska in the conventional Like Brother and Sister sense.
Phoenix and Maya also have quite a bit of this. The most notable being how Phoenix is particularly emotional whenever Maya's in trouble (See: 2-2, 2-4, 3-5). Pearl's Shipper on Deck attitude certainly helps.
There's a small statement in Trials and Tribulations in which Iris actually Dahlia Hawthorne being channeled by Maya, and no doubt trying to hurt emotionally hurt Phoenix asks Phoenix if Maya is his girlfriend. Phoenix responds with "...!", not a denial.
Some dedicated "Narumayo" shippers have compiled extensivelists of the teases throughout the trilogy.
The third game served to further fuel Phoenix/Edgeworth and Phoenix/Maya, and to make things more confusing, they then threw in Iris to boot. She once was in a relationship with Phoenix while impersonating her sister, Dahlia, and Phoenix once put his life on the line to protect her by drinking what might be poison, is also teased and appears resolved at the end of the game...except that she seems to disappear during the seven-year timeskip between Trials and Tribulations and Apollo Justice. ...well, so do Maya and Edgeworth, though.
And after their experience with Phoenix/Edgeworth, in Apollo Justice, they seem to be teasing Apollo/Klavier with Klavier's very first line! ("I'm used to being inspected by the ladies... but I admit this is the first time I've felt this way with a man!")
To say nothing of Apollo/Vera? (Apollo: "(I feel like a teenager on a first date!)")
Juniper VERY clearly harbors a crush on Apollo, to the point where she will start knitting a scarf full of hearts while gushing about him. Some have joked about how Juniper is Vera 2.0, partially because of this. (Apollo himself seems oblivious to all of it, however.)
Apollo and Athena also have a fair deal of it - small things like Klavier assuming that they are a couple fade in comparison to how the second and third cases are all flashbacks as Athena wonders why Apollo left the agency, and the fifth case... Apollo wasn't wearing that eyepatch due to the courtroom bombing, but to stunt his perception powers on purpose so he wouldn't distrust Athena due to her tells... and then, when he is given more concrete reasons to distrust her, he gets on the witness stand and begs Phoenix to prove him wrong. "How can you have faith without doubt?"
Naturally, once Edgeworth gets into the frame, the Ho Yay runs more rampant than ever, as several other characters start talking about it. Heck, even a vicious murderer almost incapable of feeling emotions mentions that they are "close enough to argue".
Despite not appearing in the game, Maya's one letter to Phoenix was enough to revive him from a very bad slump near the end of the game.
Athena also has quite a bit of this with the merciless prosecutor Simon Blackquill, specially in the fifth case when her and Blackquill's shared Dark and Troubled Past is revealed and the players learn exactly how important they actually are to each other... Blackquill is determined to protect Athena, the daughter of his dead mentor, even if that means sacrificing his own life to do so.
From the second Edgeworth game, we have Raymond Shields and Katherine Hall, a defense attorney and his client. They show the same kind of trust in each other you see from Phoenix and Maya, and Gregory mentions from their first meeting that he told Raymond to 'note', not 'dote'. Raymond won't hesitate to suspect Katherine when all evidence points to her, however.
The licensed game adapation of Tim Burton's film Alice in Wonderland takes ship teasing in a completely different direction (see the Film section above). While the movie contains hints of Hatter/Alice, the game contains hints of Hatter/White Queen.
Riki, the protagonist of Little Busters!, obviously has ship tease with each of the girls he can end up with. But more notably, he also has a veritable shitton of it with his Childhood Friend Kyousuke. Much of it - the touchiness, their tendency to get into suggestive situations together - is simple Ho Yay, but in one optional scene Riki outright admits mentally that he has feelings for Kyousuke but isn't doing anything because he doesn't want to ruin their friendship, and everything we hear from Kyousuke on the subject is ambiguous at worst and very much implying he feels the same at best. However, since there is no Gay Option, not even a comedic one like in CLANNAD, the pairing is sadly never to be. At least, not in any of the realities the player can see, anyway.
Refrain takes it even further: their last meeting before the dream world crumbles and Riki returns to the real world has Riki completely distraught, yelling that he likes Kyousuke and wants to be with him forever, and Kyousuke screaming back that he likes Riki so, so much more, all coming across in exactly the same way an Anguished Declaration of Love would. And then in the end when Rin asks Riki who he likes, we never hear a response. There's nothing that's completely incompatible with an interpretation that they're just very strong friends, but if they weren't, this is sure as hell what it would look like.
In Dangan Ronpa, there is a little bit of it between Naegi and Maizono, due to them being classmates in middle school and the only two who knew each other before Hope's Peak Academy. It all comes to nothing, as Maizono ends up dying after trying to kill someone else and frame Naegi for it. However, she leaves behind the name of her killer, written in blood. Kirigiri speculates that this may have been in repentance for her earlier manipulation.
After Maizono's death, hints of Kirigiri/Naegi started popping up. What with both Monokuma and Asahina mistaking the two to be dating when they were meeting up secretly in the sauna, Kirigiri being furious after Naegi keeps a secret from her (when early on he convinces her that they should trust each other completely with their secrets), and Kirigiri coming to Naegi's rescue in the garbage dump after his execution failed, it's not hard to assume that there's something going on between the two.
In Super Dangan Ronpa 2...oh, man. There's no question that Kuzuryuu and Pekoyama love each other very much. The real question is if the love is romantic or familial in nature. Pekoyama, Kuzuryuu's bodyguard, is loyal to him to the point where she kills one student and tries to condemn the others (including herself) to death just to get him off the island, and encourages him to use her to any means he desires. Kuzuryuu, normally a chilly jerkass, breaks down crying at Pekoyama's sentencing and risks his life in a futile attempt to save her from her execution. Plus, he actually refuses to treat her like a tool and sees her as a beloved companion, which is in marked contrast to his behavior towards his other classmates. It may be the emotionally charged atmosphere of Chapter 2's trial, but there are a lot of fans who believe there's something romantic going on there.
Pekoyama's Dangan Island route outright confirms that the reason why Hinata couldn't end up with her is because she already likes someone else, with that someone else heavily implied to be Kuzuryuu. A Valentines Day tweet reaffirms this notion. Also, in chapter 6 the reason why Kuzuryuu eventually decides to choose the Forced Shutdown option is because Pekoyama would have wanted him to, otherwise he would have chosen the Stay option just so he could be with Pekoyama again.
Gundam Tanaka and Sonia Nevermind probably get the most ship tease second to Pekoyama and Kuzuryuu. Not only is Sonia the one character to make Gundam blush, she is also the only one he doesn't refer to in a demeaning manner and clearly respects her the most out of the class. It goes as far as him referring to her as his "Dark Lady" and in one of his free time events, he tells Hinata about his fantastical image of her. On Sonia's end, she greatly admires Gundam and his hamsters, and even joins in on his antics from time to time. It's to the point where it seems that she's the only person who not only accepts Gundam's fantasies but also understands and believes them. The most apparent ship tease occurs in Chapter 4, where Sonia tagged along with Gundam whenever the group split up, the two of them showed great team work and deduction during the trial and Sonia defended him to the bitter end when he was accused of being the murderer. And if that wasn't enough, even some official merchandise pair the two together!
There's also quite a bit ship tease between Hajime and Chiaki. During one of her free time events, she compliments him on being well-built and says that she trusts him enough to carry her, all of which leaves Hajime very nervous and self-conscious. He even mentions his heart racing on more than a few occasions with her. During her final free time event, Chiaki admits that she doesn't know a lot of things, like how to fall in love with someone, and asks Hajime if he'll keep teaching her. She also asks him not to never forget about her after he gets off the island. He promises that once they escape, he'll take her to all kinds of different places.
The reveal that Chiaki Nanami actually was a real person naturally plays up the relationship between her and Hajime in the Despair arc. This leads to tragedy once Hajime becomes Izuru Kamukura, though interestingly it's still teased after—his new self very quickly takes an interest in her and starts crying at her death. He may even have regained his memories of her, which was supposed to be impossible. And it's still teased even after that—Izuru is shown to have hung onto her hairpin for years, was moved by her final words into turning on Junko, and frequently left flowers on her desk.
The Future arc teases Chisa/Kyosuke by omission: she dies early on, but Kyosuke's reaction to that provides a lot of ship fuel. Like 'I'd sooner kill everyone here than risk her murderer escaping justice' fuel. Tengan actually suggests that he loved her romantically.
Word of God states that after the first game, Junpei chased after Akane for his whole life and never found her againnote Which is technically true- they do meet again in the sequel, but Junpei decides that he was only Loving a Shadow and that the innocent Akane he loved is gone. Despite this, the sequel shows that Akane genuinely wanted to be with Junpei, it was just that she had to devote her life to saving the world from Radical-6. One of the writers confirmed that she was not lying, which lends credence to the theory that her flirtation with him wasn't as pragmatically motivated as fans thought. In VLR, Junpei's future self Tenmyouji is embittered by the whole experience, but both Akane and an alternate version of Junpei are confirmed to appear in the third game, so who knows where they'll end up?
While not nearly as obvious as with June, Junpei also has some Ship Tease with Clover. On the route to the true ending, they share a couple of intimate moments, which aren't romantic in and of themselves, but do pave the way for what can be read as Clover developing a bit of a crush on Junpei.
Luna definitely loves Sigma. This love is probably romantic in nature, and Sigma probably does not reciprocate. note However, Word of God specifically noted that, Luna being a robot, it's difficult to define exactly what type of love she feels for him. The fact that Sigma is her creator also further complicates matters.
Sigma/Phi is jossed by Word of God, and the closest they get in VLR is a rather grudging friendship.
Sigma risked his life to save Diana, and later based Luna's appearance off hers. The third game will confirm the nature of their relationship.