One thing that makes this game easier than the original Contra is that your standard weapon weapon is a machine gun, not a single shot rifle. You can cut down enemy troops will ease, though it will still take several shots to destroy artillery and armored troops. Spread and laser also return, and fireball has been upgraded to an actual flamethrower. Two new guns debut as well — crush and homing.
You can now carry two weapons — one active and one in reserve. When you pick up a new one you replace the active one. When you die you keep the reserve one, but the active one reverts back to a machine gun. If you really favor one weapon you may want to keep two of them on hand at once. Otherwise, have one spread or homing gun and either crush, laser, or the flamethrower as your other weapon. What works best depends on the situation and player.
You start the game with this weapon. It's not bad but there are better weapons out there. It has a very fast firing rate with an on-screen capacity of ten bullets, though the bullets are relatively weak. They are certainly able to get you through if nothing else is available, though you should upgrade to the spread as soon as you can. You won't actually find these in any item capsules since they are your defaults.
This weapon packs quite a punch but it has a slow firing rate, limited range, and an on-screen capacity of only three missiles. It's good against stronger enemies and a few bosses when you don't have the laser. This is a great secondary weapon, though you should always keep the machine gun, spread, or homing as your alternate since it does not work well against large numbers of enemies or far away ones (such as snipers and grenadiers).
The homing gun has a pretty fast firing rate, with an on-screen capacity of five bullets, but the bullets are somewhat weak. The bullets will track enemies and fly into them though, so that’s another plus. It is good against weak enemies, but will sometimes focus on the grunts instead of the powerful enemies, so it increases the length of boss fights. Because of this, you may end up getting killed while you wait. It is particularly useful if you want to focus fully on dodging.
Here was the weapon to have in the first two Contra games. It's still one of the best, but this time there are better weapons. It still has good range and a decent firing rate, with an on-screen capacity of ten bullets (or two "5-way" shots), though you may want to keep a crush or laser as your secondary weapon for bosses. If you stand close to the target, all of the bullets will go into it, causing a lot of damage. It’s quite a versatile weapon overall.
The laser does damage roughly on par with the crush in terms of raw power, but has a much longer range. It's one of the best weapons to use against bosses and some artillery pieces. It has a relatively slow firing rate and can only shoot one beam on-screen, so it's not so good on the actual stages where the enemies are weak but coming from all angles. It makes it a great secondary weapon.
Perhaps the most fun weapon and, despite the very short range, very versatile. It's a good weapon for lots of situations that the game throws at you. It's effective on the actual stages but it can be used against bosses if you want. It has a fairly powerful attack, especially if the target is stationary, since the firing rate is high and cumulative. An excellent weapon, but not recommended as your primary.
These items don't fall into the other category since it doesn't go into your gun slot, but are very useful weapons in the right situation.
M-80,000 Helio Bomb
This is one of the most useful items in the game, which functions like the Specials did in the first two games. The only difference is that you can store several of these for later use. You should have several of these on hand at all times for crowd control on stages or for damaging bosses. When you use them on bosses, try to get close to it so that the Helio Bomb inflicts the maximum amount of damage. The are not the most effective against the bosses themselves, but are excellent against the smaller enemies, guns, and enemy spawners that come with the boss.
You only get this item twice, and on the first stage. It will protect you from all enemies and bullets for about 30 seconds or so, though falling into an abyss will still kill you. After you stop flashing, you’re vulnerable again, so watch out for enemies and stuff. If there are two of you playing, make sure the guy with the shield is in front so that he can absorb the hits. Running into enemies will do a fair amount of damage, just make sure you back away when you're about to lose it.