Fighter, Monk, Wizard, Sorcerer, Cleric, Shugenja (from Complete Divine), Rogue and Ninja (from Complete Adventurer)

Unfortunately, you have selected a massivamente disparate subset of the classes. Fighter, monk, ninja, and rogue are four of the mais fraco classes published for all of 3.5 (with Aventureiro Completo’s ninja actually probably the worst here), while cleric, shugenja, sorcerer, and wizard are four of the mais forte classes published (especially the cleric and wizard).

And ultimately, those spellcasters are so powerful that no one without spellcasting is going to be able to keep up if they’re played at anything like their potential.

If you are going to be selecting a very-limited subset of the classes, I suggest that you take the opportunity to choose better designed classes que tem tighter overall balance. Your warriors are not powerful enough, your spellcasters are too powerful.

You can ignore the advice for everyone but the fighter and the monk – I still do strongly recommend the swordsage and warblade there – but even those improved options won’t be able to keep up with those spellcasters, at least not unless the people playing them are underplaying their power quite a lot. Therefore, I’d like to offer a more “complete” recommendation for every class on your list.

In all cases, I have carefully chosen the replacement class so that it can be a “drop-in” replacement – you don’t have to make up a new place in your setting for warblades, just use the warblade’s stats and rules and call it “fighter.”

Stronger warriors

The more “direct” answer to the question, there definitely are superior options for playing a “fighter” or “monk” than the fighter class or monk class. Note, however, that even these are still a far cry from the spellcasters you have selected (and, indeed, still are not quite up to the ability of even the weaker spellcasters I recommend below).

Instead of fighter, consider the warblade

The warblade from Tome of Battle: The Book of Nine Swords is an intelligent master-of-arms, a savvy tactician and a well-honed veteran of battle. His ability to master weapons is without parallel, and in battle he is relentless and iconic, rallying his allies around him.

Instead of monk or ninja, consider the swordsage

Também a partir de Tomo da Batalha, the swordsage could be monk or ninja, depending on the particular choices that you make. A “monk-like” swordsage would probably focus more on Diamond Mind and Setting Sun maneuvers, while a “ninja-like” swordsage would likely focus on Shadow Hand and Tiger Claw – but either would be remiss to ignore those other disciplines.

Instead of rogue, consider the factotum

Dungeonscape’s factotum is basically “the class Indiana Jones would take if he were in D&D.” Factota do a little bit of everything, and do it well. They use their wits and cunning to make it up as they go along, and are the best skill-monkeys in the game, bar none. Awesome, super-fun class.

Weaker Spellcasters

I wrote an answer dedicated to this question aqui, but because that question was overly-broad, my answer was overly-long.

But the idea is still sound: the over-powered spellcasters you have chosen could be replaced quite well by other spellcasters that fulfill similar roles and have similar narrative backgrounds. Note that these spellcasters are still very powerful, however; using these is insufficient to make the fighter, monk, or ninja classes play on even footing. Even the superior classes I recommend above are at something of a disadvantage compared to most of these; the gap is just much narrower.

For this game, I strongly recomment the following replacements:

Instead of cleric, consider the bardo divino

Bards are viable warriors, while not being excellent at it. The cleric would make a far better warrior than any of your warrior classes. The bard has some solid healing spells, especially when divine, and their music makes them fantastic leaders-of-men.

Alternatively, the incarnate might be excellent

The incarnate from Magia de Incarnum is an excellent replacement, flavor-wise, for a cleric, with a strong religious theme (an evil-aligned incarnate is supposed to literally be mal encarnado). Their powers lends themselves a bit more to the skill-monkey/support role than the warrior/healer role, but they’re overall an excellent class and judiciously awarding wands of cleric spells can make up a huge part of the difference.

If you specifically querido the warrior-priest, crusader is for you

I generally recommend replacing cleric with classes that are less devastating at armed combat, because I tend to feel that the cleric’s prowess there makes it difficult to justify the existence of, e.g., paladins. But since you have not selected paladins in the first place, you might be procurando for a more martial bent from your divine class. If so, the crusader from Tomo da Batalha: Livro das Nove Espadas is perfect – he heals his allies as he smites his enemies, and as a rallying point and commander of battle, he knows few peers.

Also, crusader is one of my favorite classes in the game, and my #1 recommendation to new players.

Instead of shugenja, consider the ... actually, shugenja’s probably OK

Shugenja is the weakest of the spellcasting classes that you have listed, and while it is more powerful than the other classes I have mentioned here, it’s probably close enough so as not to cause problems.

Instead of sorcerer, consider the dragonfire adept

Sorcerers, in 3.5, are thought to base their magic powers on trace draconic ancestry. The dragonfire adept from Dragon Magic, on the other hand, obviously gets their power from dragons. They gain a breath weapon and a number of invocations, which are at-will spell-like abilities. Similar style to a sorcerer, at a lower power level. Like the warlock, which I recommend as a replacement for wizard, below, dragonfire adepts tend to be a little on the low side, in terms of invocations known. Allowing them to learn a new invocation every level except those in which they gain a new breath effect is a simple solution that I have found works well.

Instead of wizard...

Instead of enchanter or illusionist, consider the beguiler

Beguilers, from Manual do Jogador II, get a small, specific spell list, tailored towards the casting of enchantments and illusions. They do get some opportunities to add to their list, but few enough to keep them under control. They’re also a lot of fun.

The beguiler might be the most powerful class here (I don't have enough experience with shugenjas to say for sure), so you may want to reduce it somewhat. Their armored spellcasting is a minor boon they can easily afford to lose, and as an Int-based class, 6+Int skill points is quite a bit – 4+Int might be more appropriate. Removing some or all of glitterdust, pressa, nevoeiro sólido, E / ou parar o tempo from their spell list might be good choices.

Instead of necromancer, consider the dread necromancer

Heróis do Horror’s dread necromancer is actually better than the wizard-necromancer at raising undead minions, but the dread necromancer spell list is tightly limited, like the beguiler’s, to enforce the focus on necromancy. Again, smaller list with carefully-controlled opportunities to expand it do a lot to limit the power of the wizard.

As will become a theme, changing the dread necromancer’s spellcasting to Intelligence rather than Charisma will make them more “wizardly.” The split between Intelligence for spells and Charisma for Rebuke Undead is also probably a good thing, and will slightly (but noticeably) play up the more “wizardly” necromancy of curses and debuffs, rather than the minion-master undead-army-raising that you get with Rebuke Undead, which I consider a good thing.

I’d also consider losing the ability to cast in light armor. It’s not especially powerful (it is easy to avoid Arcane Spell Failure), but the dread necromancer is on the higher-end of classes presented here, so chipping away at that is desirable. Plus, I recommended removing it from the beguiler (enchanter) and warlock (generalist wizard), leaving the dragonfire adept (sorcerer) and warmage (evoker) the only ones who have it: that seems appropriate.

Instead of evoker, consider the warmage

The warmage from Arcano completo is the evocation equivalent of the beguiler or dread necromancer. Unfortunately, being blasting-only does leave the warmage a little flat, but they are still capable enough for keeping up with my other suggestions.

Since you want the warmage to be replacing an evoker-wizard, I would switch the spellcasting to Intelligence. This has the added bonus of making the Warmage Edge feature more useful (usually, outside of very-low levels, the bonus it provides is too small to justify investing much in Intelligence, and it just ends up being a trap, tricking players into putting too much into Intelligence).

Instead of wizard, consider the warlock

Another entry from Arcano completo, the warlock is similar to the dragonfire adept, but much more strongly arcane, with abilities to conjure, dispel, divine, and transmute, not to mention their iconic explosão de eldritch. These make decent generalists; a bit on the weak side, so consider increasing their number of invocations known. I find having 1/level goes a long way. Also, explosão de eldritch goes up 1d6 every odd level... until 13th level, where it goes up every three levels. No one knows why it slows down like that, but it’s pretty common to just ignore that and use 1d6 per odd level, and that works well.

Making the warlock intelligence-based would also be a nice improvement of his wizardly-ness. It also helps the skill situation, though even com an Intelligence focus I’d still give the poor guy 4+Int skills. Losing the ability to invoke in light armor may be appropriate, especially if this justifies some more invocations known (say, 1/level, plus an additional 1 each time you reach a new tier of invocation? That would be awesome).

Tomo da Batalha: Livro das Nove Espadas

The Warblade and Swordsage classes are effectively the 'more options' versions of the Fighter and the Monk. They are slightly stronger than the fighter and the monk, but not as strong as a full caster.

BWL's Art of War Fighter

This is the best 'Fighter Fix' I found floating around on the web. Notably, it gives fighters a lot of options. Doesn't make them significantly more powerful, though, so they'll still be overshadowed by a druid, wizard, etc.

The Monk Remixed

This is the best 'Monk Fix' I found floating around on the web. Brings the Monk up to low tier 3, by adding wisdom to damage and allowing the monk to use dex instead of str to attack and damage with unarmed strikes - reduces the monk's MAD considerably, and the movement-skill bonuses mean doing Sweet Flips is something monks can actually do.

Corridas de Guerra

The 'Monk' and 'Fighter' presented here are strong tier 2 classes, able to compete with casters directly. If your group is 'casual' and 'anti-optimization' you probably won't want to use these, but the switching-out feats and building your own styles of fighting the fighter and monk do really differentiate characters from each other and give monk and fighter players lots of options to play with.

Guerreiro Psíquico

Surprisingly monk-like. Slap an unarmed strike progression and unarmoured wis bonus onto it, and it's effectively a tier 3 monk (i.e. dip one level of monk and take the Tashalatora feat from Secrets of Sarlona, a psionics setting book for eberron). The power choice, though limited, gives lots of neat monk tricks all the way from straight punching boosts to secret monk techniques to mobility tricks. You even have a 'ki' mechanic (extremely limited number of power points).

You have a couple things you can do here in terms of resources without tossing out all your classes and becoming an obsessive optimizer.

Tome of Battle - The Book of Nine Swords

Tomo da Batalha is a late 3.5e WotC book which offers a kung fu style "martial maneuvers" system that gives martial characters interesting and powerful things to do. Comes with new classes that use them which you'd probably swap in (though normal classes can get them with feat use). My group played with this a good bit before we went Pathfinder and it's a lot of fun.

Heróis de Ferro

If you don't necessarily want that kung fu feel (though given your other classes allowed you probably do) there's Monte Cook's Heróis de Ferro, which has an alternate, more complex system for martial characters for 3.5e. Third party but hey, Monte Cook. There are a lot of changes and it involves a lot of mental investment but it's a well-reasoned replacement martial system.

CharOp Guides

You could even the playing field by looking up optimization guides and applying them in collaboration with your fighter and rogue characters. See Where can I find a good [MyClass] Handbook CharOp List? to find such guides.

For example, I play a Barbarian in another 3.5e game, and we've incorporated the Pathfinder rules for Rage powers and Rage rounds per day. It seems that the Pathfinder Fighter isn't any better than the 3.5e Fighter, however.

The "simple" answer is to just extend what you're already doing with the Barbarian and use the Pathfinder versions of those classes, including all the archetypes and feats that are available. That should be more than enough to grant the extra versatility you're looking for.

A fighter's shtick is feats: Let him have the feat-every-level that a Pathfinder fighter would get, and the broader array of feats to choose from. While this doesn't garantir more options in combat, the way rage powers do, it gives the player the option to choose a variety of feats they find fun, and that no one else can do. For example: the Step Up and Strike chain or the various feats that require Foco Crítico to make critting more exciting. Likewise, taking an archetype that supports the characters chosen combat style will grant them new options that they have no other way to get, such as the Archer archetype's Trick Shot feature.

For monks, I highly suggest combining the above advice with the Qinggong monk archetype, which will let the player extensivamente customize their monk. The key word with that class is "can", so they can keep all the powers they like, and get new ones to replace the ones they don't. There's also lots of style feats which provide extra options in combat, and monks are quite good at qualifying for them.