In RPGs with an Arbitrary Headcount Limit, your traveling party may sometimes be too large for the game. However, when you fight with your arbitrarily reduced team size, and then you lose, you still get a game over even though the rest of the characters are still up. Sometimes the characters you do put in your party are Lazy Backup as well; in this case, you lose if the Player Character is killed, even when the rest of the party is still alive and possesses means of resurrection.
Some games make the backup more lazy than others. In addition to losing the game if the on-screen characters are defeated, there may be arbitrary rules for switching characters:
You can't switch out characters that are currently unconscious or dead (permanently or otherwise).
You can only switch characters when not in battle.
You can only switch characters in certain locations, such as towns or the world map.
Justified in games featuring Final Death if a plot-critical character is killed. Often times, this trope isn't limited to just Video Games, either, as many other mediums, especially Anime, Manga, and Comics will be just as guilty of it.
In Drakengard 2, you only control one character at a time and can switch between your four party members pretty much whenever you want. If your currently-controlled character falls in battle, it's Game Over...even though one of your party members literally cannot die and actually regenerates health while he's on the sidelines.
Mega Man X7 lets you choose two Maverick Hunters and lets you switch between them on the fly. If one of them runs out of health, though, you lose a life and have to restart the stage. Where did the other Hunter go? Mega Man X8 fixed this by simply switching to the still alive hunter while the defeated one slowly recovers.
In Guild Wars, a wipe is triggered if all PC members of your party are dead and no NPC members have a resurrection skill they can use. While this is normally alright because those NPCs aren't going to last long on their own anyway, it can be annoying in situations where finishing off the enemies you were fighting (which may not be beyond their capability) would trigger a cutscene and/or recharge their Resurrection Signets.
Role Playing Game
Chrono Trigger: Given that you can switch party members anytime out-of-battle, why can't you do that after three of them get knocked out in battle? (If this is justified by their having to use the Gate Key, then why can you switch party members anytime out-of-battle anyway?)
A less justifiable example occurs if Frog challenges Magus for the second time and loses. You'll get a game over even though the other two party members just walked off a short distance.
Averted in the extra dungeon in the DS version where the main party is trapped and the reserve party comes to free the main party
Normally in Chrono Cross you can only switch party members at save points, unless the plot calls for a certain character, at which point they just walk on from offscreen. This leads to some strange moments, such as the fight with Bonus Boss Dario. Depending on your party composition, up to two extra party members will walk up right before the fight to explain the plot, but then will just stand there as your party gets slaughtered without doing anything. A very sad example, given both this particular plotline and the fact that he's That One Boss.
In Golden Sun: The Lost Age, Kraden definitely wouldn't be able to handle combat, but couldn't he at least pull out your healing items to help out when you lose?
Also averted in that by the end of the game, you'll have eight characters, but only four active in battle at any time. If your first four are knocked out, the game will automatically switch to the other four characters if any of them are still alive. You can also switch individual party members between turns.
Golden Sun: Dark Dawn also brings in the rear guard if the entire front line falls in battle, and allows you to rearrange the party mid-battle. Rear-line characters will also automatically switch in during the Ancient Devil battle after someone falls prey to Demon Sign, and allies KO'd under Demon Sign will be placed in the rear instead of wasting space on the front line.
Subverted in the first game Atelier Iris: Eternal Mana, you can either choose to replace a fallen member or keep it thrashed on the field so you can revive it.
In Cross Edge, there is a potential cast of over 20 characters; but you can only ever have 4 at a time in your party, and if you die, it's game over. Regardless of the large group that is there, watching.
Averted in the mech battles of Xenosaga 3. If one mech gets knocked out a backup mech will automatically jump in and replace it. Unfortunately there's only one backup mech so any other KOs are down for the rest of the battle.
Final Fantasy IV averts the trope by enforcing it party headcount limit with an iron fist. Once the party's full, any new additions are preceded by one of the active party members dying, leaving, or otherwise being forcibly taken out of the action. The one time it seems like you do get too many party members, he turns out to be a monster and attacks you, never actually joining the party.
Final Fantasy VI: Mostly averted. Your extra party members are left behind in Narshe or the airship, and you can't switch unless you go back there; no instant switch zones. Until you get control of the airship, switching inevitably involves a very long march most of the way across a continent.
A bit strange in the Final Boss fight, where you place all your party members in a queue. After finishing each tier of the boss, unconscious characters are replaced by the next characters waiting in line — but lose all four members at once, and it's Game Over.
By contrast, when you're using the Moogles to save Terra, or battling Kefka for Narshe's Esper, if one party is KOed you do not receive a Game Over, but the losing party is revived at the back of the field with 1 HP apiece.
In the early stages of the game you recieve a temporary character named Banon who is vital to the mission ahead, so if he falls in battle it's Game Over (perhaps he is allergic to Phoenix Downs).
Final Fantasy VII: considering you can switch out characters at any time on the main map and further considering your party can and does go on without Cloud for a period of time means your backup is incredibly unwilling to help.
Fridge Logic : the 'PHS', used for switching party members, is a mobile phone. The backup thus isn't lazy, but is too far away to help. And fighting their own off-screen battles - non-party members still get some experience (half what the active party get) in FFVII. Of course, this just raises the question of why split up in the first place?
Fridge Brilliance: They're traveling in smaller groups because they're on Shinra's hit list, so they want to be able to travel quickly and lessen the chances of them all being captured. It's a guerrilla tactic.
Possibly the worst case is the fight against Ultimate WEAPON: it takes place on the Highwind, so all the other characters are right there, doing nothing. Maybe Cid's keeping an eye on the pilot and Yuffie's busy being sick, but the others could lend a hand! At least on the world map the implication is that the rest of the party are at a nearby town but not necessarily near enough to lend a hand. On the bright side, at least Ultimate WEAPON isn't particularly difficult - but you'd think they could lend a hand against EmeraldRuby...
Particularly egregious in Final Fantasy X, which has a sort of "tag team" mechanic, in which you can switch party members during battle, but only on that character's turn. If a character is KO'd, then their "slot" is wasted because you can't bring anyone else in until you revive them. Thus, having all three currently active characters KO'd at the same time is a game over, even though you can have as many as four other characters waiting in the wings.
Worse still, some enemies will petrify then shatter your teammates, depriving you of their spot for the rest of the fight - when the space could easily be filled by a back-row ally. (Fortunately, they're only mostly shattered, I guess, because they come right back once the fight's over)
Averted in Final Fantasy XII: You can only fight with three party members at a time, but you can swap out a front-liner for a reserve PC at any time, AND if all three front-liners get KO'd, the game forces you to switch in at least one of the reserve PCs. You can even target your reserve party-members with buffs and heals, so you can have your secondary party revive your primary after a total-party-KO. In fact the only way to die is to have all six members of your party KO'd.
There is a boss that has instant death attacks - the only way to win against him is to constantly raise the characters who are not in the front line.
The plot of Final Fantasy XIII stresses teamwork and the power of True Companions, but you can only have three guys in your party at once in each battle. Paradigms make up for this discrepancy, however.
What makes this game a particularly annoying example of this trope, however, is the fact that the game's over if ONE particular character - whoever is the leader at the time - goes down. The other two can be standing and perfectly healthy, but it doesn't matter. Apparently only the leader has the phoenix downs.
This means you can lose an infuriating number of battles - battles you'd expect otherwise to easily win - when all of your enemies gang up on your party leader. It defies explanation.
Dragon Quest IV does it both ways. There are sections—caves and things—where the wagon won't fit, and if you die in that section, it's game over. In areas where you do have the wagon—the final boss is mercifully one of them—you can not only switch members, but when all four of your active party members die, the next four will jump out to replace them. I seem to recall there being text to the effect of the new character shoving the dead character's ghost into the wagon.
In Dragon Quest V, however, the cart fits anywhere, and the alternate characters (including the Mons) automatically switch out—in fact, it's virtually impossible to beat the final boss without using this system. Also, if your main character dies but there's someone else active in the party, he will be automatically revived by the other character, and that includes the panther.
Used, sadly, in indie RPG Hero's Realm. You have sixteen characters divided into four parties but if one party goes down, the other three won't lift a finger to step in and it's game over for you!
Happens in MS Saga, a GundamRPG. You have three front-line fighters at a time but up to six characters in your party total (and, toward the end, you can have seven or eight allies at once!). It's game over if all three of your front-liners die, even if your three in the back are fine (to say nothing of anyone not actually in your party at all).
Baten Kaitos: Eternal Wings and the Lost Ocean is particularly irritating about this. Origins averts it by only giving you three party members.
"Kingdom Hearts II" Are an aversion to this with an ability for party members to switch out right before they're KO'ed.
Also played with a little: While it doesn't matter if your party members are still up if Sora dies, King Mickey can intervene in certain boss fights if you get KO'ed. The catch of sorts is that he's not even a party member—he's just checking in on you.
Vesperia even lampshades this by having members that haven't been in the active party in awhile complain about being left out of the action in skits. They seemingly just stand around watching others fight.
Averted by Tales of Hearts's Link Attack system, which lets you call in non-fighting party members to perform attacks or spells. Linked attacks can be guarded but not interrupted, making it often useful to leave one of the healers in the back row.
Justified once in Tales of the Abyss, during the last fight with Arietta, a Duel to the Death, the entire party is there, but Arietta sets the terms as herself and her two monsters versus four of the heroes.
Justified again at the end of the game; a skit before the final battle establishes that the two party members not fighting the boss will be securing an escape route. However, some of the party seems surprised at this plan, suggesting that this isn't standard procedure for them, so this justification only highlights the fact that the entire rest of the game has featured lazy backup.
In Tales of Graces, a fight with Richard is made exceptionally annoying by first depriving you of one party member slot (instead of 4 characters, you fight him with 3) with no good plot explanation for why Malik or Pascal were sitting this one out, and then by giving you a time limit for a trophy. Needless to say, there would be much less restarting of this fight and all the long cutscenes involved if the dev team hadn't placed such artificial constraints on the player.
Pascal and Malik were helping to evacuate the citizens of Lhant.
Mario & Luigi: Partners In Time has an odd take on this: When one of the adult party members is KOed, their junior counterpart pulls them out of the fray and takes their place. If both Marios or both Luigis are knocked out, the other brother has to carry them around, making battles much harder, since it takes longer to jump over attacks.
Mario & Luigi: Bowser's Inside Story does something similar. Although at a certain point on Mario and Luigi can leave Bowser's body, and both teams can fight pretty well, you have to have at least one character on each screen left alive, otherwise you get a game over. This is made more interesting in one battle, where the boss is fighting Mario and Luigi, but also harms Bowser with some attacks, and you have to keep Bowser alive during the battle as well. A Dummied Out battle item that lets the Bros heal Bowser implies that this was going to be standard procedure.
Riviera: The Promised Land also has this. The game does comment on why only 3 characters can fight, but there's no comment on the ones who are not fighting tagging out the ones who are down.
Avoided in the final battle of Sailor Moon: Another Story. Losing with Sailor Moon's team results in Chibi-Usa's party fighting the boss (which is actually made slightly easier). Winning with them produces a slightly different ending.
The Wild ARMs 1 remake Alter Code F may have the laziest backup ever. You have 6 characters; the three originals and three "secret" characters. Only 3 can fight at once, however. These characters always go everywhere together, as evidenced by the fact that you can switch characters in battle. If one character drops in combat, you can swap them for one of the others. However, if all 3 of the current characters drop, you lose. Even if you had all 3 secondaries waiting right there. Apparently, the shock of the current characters' deaths causes them to abandon their friends and give up the quest.
And the gameplay of Wild ARMs 5 works exactly the same way, unfortunately.
In Devil Survivor you can deploy a maximum of four characters in a given battle. This isn't particularly bad for most of the game (as it spans 7 'days' and only up to 5 characters can be recruited in the first 6, meaning at most only one unit will sit out at a time). On some of the final routes though (Day 7) specifically the most difficult one, up to ten characters can be recruited. More then double the deployable limit.
Well, in Shin Megami Tensei I, II, and Strange Journey, there's a reason for the lazy backup. Your COMP doesn't have enough RAM for that. And even if it did, demons have to be physically summoned — if your character is dead, there's nobody around to summon the backup out of your COMP.
Also, the majority of demons only respect strength, and are essentially hired mercs anyway. If you get beat up, why should they bother saving your weak ass from death at the risk of their own? You simply weren't tough enough, and they aren't getting paid enough for that kind of crap.
Same problem in Devil Survivor 2. There at least part of the time you don't have more than four party members or the game tries to justify it with a cutscene showing the backup doing something else while you're on the front lines, but by the midpoint of the game you can have far more than four characters available but still only able to deploy four.
In Breath of Fire IV, you can only fight with 3 characters at a time. However, sometimes in battle the camera will pan behind to show your backup characters, who will cheer for you and may recover some of your HP. And yet if all three characters are KO'd, you get a game over. This is particularly aggravating because you know your back up is literally right there, but they won't lift a finger to revive you or take over the fight.
Those backup characters aren't just for show - you can tag them in at any point in the battle, just like FFX. You still get a big fat Game Over if your frontline threesome bite the dust, though.
In The Legend of Dragoon, while traveling with a party of 7 characters if your 3 active characters got KO'd it is a game over, despite being able to swap out characters anywhere except in battle, with the exception of Dart.
Justified in The Reconstruction; Wadassian law restricts your guild to six armed fighters at a time, so other characters aren't allowed to intervene.
Although, this still begs the question of why they still don't do anything in the final chapter, where Wadassia has been reduced to ruins and you're fighting to save the entire world.
Averted in Endless Frontier. "Those characters you never use" can unleash a support power at any time during another PC's combo, unless the main player character is using a skill or ultimate attack. Or you haven't got the SP. Or you've used all of your support powers already for that combo chain.
Averted in Science Girls - only your front row of girls can take actions during combat, but you can swap characters in and out of the front row at any time, and if a front-row girl is knocked out, a back-row girl will automatically step up to take her place. Only if the whole party goes down will you get a game over.
This is MOSTLY avoided in the Mana Khemia series, as you can switch in your back row even when your whole front row goes down. However, a full party in the first game means seven members, and so one member is delegated to stay out of the battle for no good reason.
In Lufia: the Legend Returns , you have a total of twelve playable characters (well, actually, 13 PCs, but who's counting), of which number you take nine to make you company during battles. Yep, NINE, which means that every time the enemy uses a multi-target spell, you will have most of your buddies right beside you to suck it up with you. And you can only make three moves during your turn. Don't worry about the healing though. Melphis and Yurick have everything you need to put your party back on track in just one spell.
If the 3 front line units are defeated, you get a game over despite that the others are still up and well.
Etrian Odyssey. You have a guild of 30, but you can only bring five people at one time. If that party dies, it's game over. Even if it's a party of fresh recruits, and the rest of your guild is max level.
One of the Bobobo-bo Bo-bobo RPG for the GBA averts this, by letting you change party members during battle. It's still Game Over if the 3 front characters die. The previous one plays it straight.
Less obviously justified in Dragon Age: Origins, where the Warden is likewise a mandatory party member: at least one Gray Warden is required to stop the Blight by the rules of the universe, and Alistair (the only other Warden among the Companions unless you replace him with Loghain) is more comfortable with being the sidekick even though he technically outranks the PC. Origins has another problem, though...
Lost Odyssey has this. In this case it's probably for the best since some of the characters are immortal and will always automatically revive after a while, so it would be impossible to lose the game otherwise.
In Enchanted Arms, this trope makes the Golems largely useless after getting all the human party members. Since you can't switch in battle, you might as well fill the party with the humans so they get more Experience Points, instead of wasting it on a golem that will probably get replaced by another one soon.
In Super Mario RPG, you eventually get a total of five party members, though you can only take three at a time with you. Should your main three die off, the remaining two won't count. There's also the Duel Boss occasions with Jonathon Jones and Dodo. The latter is a bit more understandable, but the former is just egregious because the rest of your party is literally standing at the sides watching you fight. Keep in mind this is one of the RPG's where it normally doesn't matter if Mario dies, either.
In Sa Ga Frontier, you can have a party of up to fifteen, but you can only ever have one five-person team battling at once. If everyone in that team dies during the battle, it's game over. Therefore, unless you like to have all your characters evenly ranked, you'll probably only level and use one team, and gather other characters only to experience their stories, see their cutscenes, and use their items in the communal inventory.
Possibly justified — characters in parties you don't use will restore a small amount of WP/JP back if they don't fight. So perhaps the other characters are resting off to the side away from the enemy.
Averted in the first Arc the Lad game, where all your characters always take part in the fight. played straight in the other episodes: even when you have a dozen human characters and even more mons, they do not take part in the battle: sometimes justified when the characters try to infiltrate enemy facilities, but why would they no go all out when they openly attack the Big Bad stronghold?
Star Ocean allows you to have eight characters in your party, but only an active party of four. However, the inactive characters aren't on an airship or in another city or anything - they are very obviously travelling with everyone else, and you can switch them in and out of the active party at any time outside of combat. And yet they do nothing when your active party get creamed by a powerful enemy, and the game ends with the defeat of the active party even though you literally have a replacement party waiting.
Averted in Star Ocean: The Last Hope, as you only get a game over when the entire team is wiped out. However, you're only allowed to switch characters in combat one at a time and with a time delay between switches. Because of this, getting your active party KO'd generally means anyone you switch in will die alone before you can switch in another.
In the Baldur's Gate series, the game ends instantly if the main character dies, regardless of how many characters in the party happen to be capable of casting Raise Dead or Resurrection. This may be justified when you actually die because as a Bhaalspawn the divine part of your soul rejoins your father and presumably cannot be retrieved, meaning even if you're revived, you can no longer affect the outcome of the prophecy and thus the game is effectively over, even if revived (which is why setting a contingency to resurrect yourself works just fine, but ends the game anyway) (like what happened to Sarevok), and it would require a Resurrection spell at minimum since your body disintegrates, raise dead requires the body be mostly intact or use another spell to make it so, but the same thing happens when you're petrified or Imprisoned. That it doesn't happen to Imoen is another discrepancy.
Possibly justified in Touhou Labyrinth, both because (as usual for the setting) nobody is really in mortal danger, and in that your party members are leaving all the time anyway, as they get progressively more bored wandering around the dungeon. ("Motivation to not abandon you" is an individual and trainable attribute.) If you lose your current frontliners, everyone else simply wanders off at once. You can switch out teammates in combat, and it's assumed you'll be doing so.
Of course, if everyone you have at the front lines is defeated in combat, it's still a game over, even if you have 8 other people ready to fight.
Eternal Sonata builds your party up to 10 (Xbox 360) or 12 (PS2) characters — provided you brave the Bonus Dungeon, that is — but only allows three active characters in a party at one time. You can switch any time you're neither in a battle nor in a cutscene, but no character will even move to replace fallen characters, and if all three of the ones you chose fall, it's game over. (At least any active character that's not dead can revive any that are, provided they have the right item.)
In Legaia II: Duel Saga, there will eventually be five playable characters, and you can freely switch the party order between battles. However, only three can participate in battle, and if those three fall, it's game over.
Shoot Em Up
In Star Fox Command, it's entirely possible to have several characters attack the same base or enemy on the map, but you have to pick only one for the fight anyway, so the only benefit is being able to choose, and having multiple shots at a tough enemy in the same round.
Averted in Star Wars: Republic Commando, where your squadmates will revive you if you're down, as long as at least one is left standing. Once all are down, though, it's game over.
In Contra Force, the player can switch between four characters, each with three lives. However, if your current character dies and loses his final life, the game will instantly end no matter how many lives the other characters still have. This doesn't apply in 2-Player mode, in which another player can switch to another character if his current character loses all of his lives.
In Firefight mode in Halo ODST and now Halo: Reach, even if you have ten lives left, you only have as many humans on the ground as you have players (for obvious reasons). Interestingly, though, there's "reinforcements" which brings on ally back even if you have no reinforcements.
In The Umbrella Chronicles, a rail-shooter light gun game set in the Resident Evil universe, if you have no player two, your so-called "partner" won't lift a finger to stop you from being eaten alive or beaten to death. You can't switch to them either, even though they're supposedly right there.
Averted in The Darkside Chronicles, in which they automatically fire on enemies and avoid getting in your way, although you will occasionally have to help them in 'mini cutscenes' where they get grabbed by a zombie.
Real Time Strategy
In Dawn of War 2 you can deploy 4 out of 6-7 available squads in any given mission. Others will not bother going down and helping out even if all your squads are incapacitated, and a dropship is sent after them for emergency extraction. Even worse in the expansion pack Chaos Rising, where for the ultimate battle the entire Chapter drops on the battlefield...except for those you don't select.
In Star Wars Empire At War, during the Empire campaign, you are given several Interdictor Star Destroyers, which can generate a gravity well, preventing the enemy's escape into hyperspace. This ability is used during one important and required space battle. However, while the Interdictors are generating their gravity well, they cannot attack enemy ships and cannot stand up to much fire. You can build more Interdictors if you want; however, if the Interdictors given to you for free by the Empire are destroyed, you automatically lose the battle, even if you have other surviving Interdictors. The Empire only gives you two free Interdictors until both are destroyed - two more are given to replace the destroyed ships.
Turn Based Strategy
In Final Fantasy Tactics you don't have to send Ramza into random battles, but if you send in 5 redshirts and they lose, the game is over.
Final Fantasy Tactics Advance attempts to avoid the trope by only making storyline battles become a Game Over should everyone be wiped out, but it also still makes no sense for the game to end if Marche gets sent to jail during a non-story battle. One would think someone in his clan could post bail for the kid...
Because only so many units can be deployed on the field in the later chapters of any given Fire Emblem game, one has to wonder what all of the units you haven't chosen are doing. Sometimes, this is Hand Waved by saying that they're being given other duties or you have to be sneaky or some such and too many units would blow your cover, but, a lot of the time, it's never explained.
Though Chapter 17 of Path of Radiance does more or less avert this trope as you can call in reinforcements of your own (though, since they can do this, it would be pretty cool if they did as more than once as a one level gimmick), but at the same time making the other cases even more egregious since it makes it clear that they aren't doing anything else while you're off fighting.
Also averted in Genealogy of Holy War. You can bring all available units into every battle, though this is mainly because you control two different generations of smaller-than-average groups. Also, you'll want a few units defending castles instead of fighting on the front lines.
Averted much more reasonably for the Endgame of Radiant Dawn; your selected team storms the enemy stronghold while the rest of your army stays behind to protect you from the risk of a pincer attack... specifically because the enemies are all enemies you've killed previously and were raised from the dead solely to get in your way, and will continue to return indefinitely until you take down Asherah.
Interesting example in Shining The Holy Ark where you can only hold four members in a fight at any time but you can freely switch between them, switching dead members or live ones. Yet you still lose if all three of your characters die in the main battle.
Also from the Shining Series, Shining Force II only allows you to have twelve members, and they can only be switched out when using the Caravan. Justified by Rhode when he explains that the Caravan can only carry miniaturized people and items, and thus, are unable to take over for "exhausted" party members.
The original Shining Force game A Legacy Of Great Intention has no such handwave. Instead, it has characters on deck wait patiently while you're thrown in jail, while the ship your main 12 is battling on is set fire to, and throughout all the climactic battles. If you talk to them in your headquarters, they'll say they're ready to fight or enjoying the rest period.
Played with in Shining Force III where is is played straight for most of the game but then in the last battle your remaining force is preforming their own battle at the same time.
Any TBS where you can choose not to deploy some of your units at the beginning, as there typically is no way to call them in later. If losing the battle does not result in a Game Over, those backup units are lost as well.
Dragon Ball Z is guilty of this at times. In any given fight, there will typically be 2-3 characters standing around watching as one person, by himself, goes up against the Big Bad.
Though this is generally because the guys not fighting don't have a prayer of going up against the Big Bad and are essentially risking their lives just to be moral support. And when the guys doing the fighting can casually destroy planets, you'd want to stay clear of either of them inadvertently hitting you when aiming for somebody else. Jumping in is a very bad idea.
There's one fight where all the characters were actually close to the Big Bad in power (Piccolo and Androids 16, 17 and 18 vs. Cell) and had they all dogpiled on him, he would've been dead... whatever Cell is. Of course, they were idiots and attacked one by one. Even Android 16, who knew how strong was Cell, waited until he could fight alone to attack.
Not really. At the time Cell jumped them, Piccolo and 17 had just been trying to kill one another so it makes sense that they didn't join forces. Also, Cell had devoured enough people that he was significantly stronger than anyone except #16 at that point, and even then the two of them were just about even with each other. Well, until Cell ate #17 and was suped up to the point where he could blitzstomp even #16. Of course, when Trunks and Vegeta showed up to fight Stage 2 Cell, they played this trope infuriatingly straight, to the point where they started fighting one another when Vegeta tried to let Cell achieve perfection.
Justified during the Cell Games since it had the same rules as every other fighting tournament in the show. In this case, however, there were 3 people on the sidelines who were at least a decent match against Cell (Goku, Vegeta, and Trunks) and could've jumped in at any time until Goku sacrificed himself, at which point they lost the best back-up.
Again, at this point Goku was so strong that Vegeta and Trunks thought that he was the only one who had a chance against Cell, and Goku himself thought that Cell had just been playing with him, which was underlined when a worn out but impressed Cell offered to let a drained Goku eat a senzu to make the fight be on even terms. When Cell tried to get Gohan to go all out, he was spitting out Cell Jrs that were capable of fighting Vegeta and Trunks on even terms.
Parodied (of course) in Dragonball Z Abridged. Piccolo is perfectly willing to watch Tien get beaten savagely by Nappa and shrugs it off to Gohan as a matter of honor not to interfere... while Tien begs and pleads for his friends to help him.
Gantz does this to an annoying degree, as characters will stand around and watch their friends fight and die without lifting a finger to help.
Let's just say it happens in most anime where the main story revolves around fights between the main characters and the villains.
Averted in Bleach surprisingly often, especially after Soul Society. Starting with Hueco Mundo, there'll be lots of times when one of the protagonists jumps in while another's fighting someone. For example, Yoruichi and Urahara double-teaming Aizen.
Though this is more likely to be played straight the stronger you are. And in some arcs, the combatants won't fight until they can be paired up with an enemy, so that no one has backup. ...Or strategy...
Played with in the Fred Perry comic S-Guild. The backstory is that the heroes lost, everyone died, except the back-up. Which was comprised of 'those characters you never use.' So, they were under-leveled, etc...
In Death Or Glory, when Cain fights the Ork Warboss, the other orks don't intervene because the former had essentially challenged him to a duel (or rather, attacking Cain would imply their leader couldn't take him on and be a challenge to his authority) while Jurgen doesn't fire because if the orks did attack they were both screwed (a rare recorded instance of Jurgen telling Cain he can't do something).