Hey man, i just got SNES9x and i have been playing nothing but roms in my spare time, i just got done beating mmx3 again, i love that game, for bosses,
blizzard buffalo
toxic seahorse
tunnel rhino
volt catfish
crush crawfish
neon tiger
gravity beetle
blast hornet
follow that for the "weakness pattern" and you shouldn't have any trouble getting hit most of the time , except tiger and seahorse, crush crawfish, just stay on one side of the wall, keep dashing up it, and when he sends out those little orange holders, let one grab you and still kick up the wall once, it you do it right he sends a claw out to get you diagonally up the wall, but you fall down and should have a blast for him, quickly run back up the wall and repeat, he is super easy that way,
as for Bit Byte and Vile, they appear randomly in the boss stages, ( those rooms in the middle of the stages that you go into and nothing happens ) after you beat any two bosses they start appearing, You can blast them away with normal weapons and face them later or you can use the boss weapon to finish each one off for good!!!!
Bit- frost shield
Byte- tunnel fang
Vile-spining blades
by defeating them the first time with the specific boss weapon, you will open up new bosses in the first two Doppler Stages,
When you defeat Bit and Byte with the boss weapons, you will open up a boss called "press Disposer elephant,in Doppler Stage 1. He's got some mean attacks and utilizes a garbage dump that drops broken reploids like mmx1 that fire at you and drops big clumps of garbage, take out his snout and he'll spread acid on the ground, stay on the walls and when his snout is gone just blast him, you can blast above his snout to damage him, its the only way to hit him , he has some claws but you can easily dodge them,
When you defeat Vile with the boss weapon you will open up a new boss and a mini boss in Doppler Stage 2,
NOW THIS IS IMPORTANT!!!!!!!!!!!
You have to have Zero, if you used him before hand in any other level and he died, you cannot use zero anymore and this will be no good, When you get to a certain part in stage 2, there will be these snails crawling up sets of spikes, when you reach the very top, there will be a gate entrance to a boss room, before you enter switch to Zero and prepare for a mini boss fight with Zero, This boss is a piece of cake, just charge up till your green and fire off 2 blasts and leave the green aura around you, when you enter the battle, just him with the sabre blast and he should die if not he is almost dead, try to range attacks because if you get to close he will take off 1/4 of Zero's health bar, major damage!!!!!! When you beat this boss The bug will fall on Zero and take him down to one bar of health, X will come in and Zero will tell X he can't go on but the battle is tough, so Zero gives X his beam sabre, and X can charge up and use it!!!!!!!!!!!!!!!!!
The beam sabre is extremely useful, because it will take off half the energy of any of the 8 mavericks, and if you hit some bosses the right way, it will do a continuous effect which can almost take the boss gauge 3/4 away, this attack is extremely useful on any of sigma's forms, and the mavericks / doppler
After that you will go back to X and enter another boss room and fight a huge Octopus / Squid , not sure what it is, stand under neath it, and use the traid thunder or use two Beam sabres and it's history
Beat the mavericks, Doppler, Sigma / I II III and voila! you've won
As for the heart tanks , sub tanks, ride armours, and capsules, they aren't that hard, and you should figure them out easily, just remember that some items require you to charge a certain boss weapon up to get some items, which are the , body armor, Kangaroo, Hawk, Head Locater, heart tank,
Use a fully charge triad thunder in tunnel rhino's stage on the boulder's blockin the two items, the second one is the head locater which enables you a layout when you enter any of the 8 mavericks levels and the red blink is where a item is held, the layout it gives you is reasonalby easy in comparison
As for the capsules, the special red ones, you can only hold one of the upgrade chips that expand 1 of the four blue upgradge capsules, Do not use any of the red capsules for a reason,,,,,,,,,for you can have the GOLD ARMOR the ultimate armour of MMX3
GOLD ARMOR: To get the gold armor, you need:
8 heart tanks
4 sub tanks, not sure if they need to be filled or not
all the ride armors (4)
all the Blue capsule upgrades, Do NOT USE ANY OF THE RED CAPSULES OR your SCREWED!!!!!!!
Go to Doppler Stage 1 , and after you destroy a Ride armor with a collapsing ceiling there will be a room with chutes spewing out Spiked Balls that roll towards you, The very first one that you see there will be a hole to your left, fall down and cling to the left side, there will be a hidden opening as you slide down the left side and there will be a red capsule , allowing you to use all the red capsule abilities which are
Armor power up, Stronger defence
Mega Buster , Hyper charge, allows you to use certain amount of charged dual shots, get hit to recharge it
double dash, preform 2 air dashes of your prefernce, extremely useful in some boss fights, EXTREMELY useful in the first sigma fight and the "chase"
Energy chip, the most useful ability in the game, stand still and your energy bar will replenish if you have taken damage, remain standing still and it will fill all your sub tanks as well!!!!!!!!!!!!!!!!!!!!
Well buddy i hope this is enough information for you, have fun!!!!!!!!!!!!!!