[1cc] Metal Slug: Super Vehicle-001 - ALL clear

Wanted to do that for a long time but never got around to actually doing it. I first played this game maybe 20 years ago and the games from this series always felt impossible to 1cc to me. They're very stressful because they give you no extends, you have a massive hitbox, die in one hit and have to take gravity into account when dodging (unlike top-down shooters or regular shoot em ups) so it's easy to be trapped in a corner, you don't have screen-clearing bombs to save you if you're trapped, and the games tend to be super long, but that one is pretty short so it's fine (well, the run is 30 minutes long but compared to the rest of the series it's short). You also spend a lot of time in the tank which takes 3 hits to explode so it's not too stressful when you're inside. And you can abuse i-frames when you exit the tank for some attacks, but I avoid doing it because it means leaving the tank for a moment.

As long as you take your time and if you have good strats, the game is actually manageable and very fair, aside from a few tricky areas. The timer is extremely generous, and probably was only added to make sure people don't spend 3 hours in the arcade milking a specific spot for points/fun. Time passes extremely slowly and is refilled at invisible checkpoints that feel like they're only 3 meters apart from each other, so if you're not scoring you can just safely ignore it. It has a few traps but once you have them memorized and don't rush they're easy to take care of. Only exceptions are the Stage 3 midboss which is always stressful and can just jump at you and knife you in a second, and the first half of the final stage before you get the tank which is very tricky. Also the final boss is super long and you'll probably make a mistake or two during the fight, so it's very important to bring a full-health tank against him.

This could really have been a no-miss and it's frustrating, but the rest of the run was good. I didn't score, since it partially implies milking one specific spot in Stage 5 for 10 minutes and losing 2 lives on purpose to refill the timer and it makes the clear harder (but it brings around 1 million point). One interesting aspect of scoring, however, is that you get a 100k bonus in a stage if you finish it with at least 10 prisoners freed. You can get this number by finding hidden prisoners, but unfortunately I didn't really memorize their locations before going for runs and they're well hidden. You often have to shoot specific spots for a certain amount of time so it's unlikely you'll find them by accident during runs. There are also some hidden prisoners by stalling for a long time against the 3rd boss, or at the very beginning of the 4th stage, and again, it's unlikely you'll get them by accident.

Maybe in the future I'll go for a run with better scoring or a no-miss, but for now I'm happy with that, it was something I wanted to do for a long time.

Various advice I can think of:

Just take your time really, no need to rush.
For most bosses, you can just spam your grenades and they should die quickly, with the exception of the final boss. I am referring to the hand grenades and not the cannon, which is pretty slow and with low DPS. You can use your grenades simply by "crouching" when in the tank.
The midboss in stage 3 is known to be kinda annoying but if you stay directly above him he's not impossible. When he inevitably moves up, just go out of the way and he'll quickly go back to the bottom. I don't bother trying to grenade him, just the pistol should be fine as he doesn't have that much HP. Also, try to save your machinegun ammo to bring it against him.
If you press the first 2 buttons when in the tank you will automatically eject and your tank will enter kamikaze mode where it will just rush forward and self-destruct, which kinda sucks and I can't think of a moment where you wish that. What sucks more is that you're very likely to press these two buttons together accidentally (since they're the shoot and jump buttons...), be very careful.
You get a lot of i-frames when you leave the tank (not just for the kamikaze attack), which is very useful because it's hard to dodge while you're using it. Abuse this for some boss patterns that would be otherwise next to impossible to dodge, most attacks are super slow and you'll see them coming.
In Stages 4 and 6, the tank is above some barrel full of explosives: get in the tank before blowing this, otherwise you'll lose it and it will be a big problem.
Sometimes when you're in the tank, an enemy tank will come from behind (Stage 3 near the end, sometimes at the beginning of Stage 4, a big one near the end of Stage 5), for those you can simply crouch and shoot backwards to kill them safely.

00:00 Mission 1
02:36 Mission 2
06:50 Mission 3
11:26 Mission 4
17:04 Mission 5
22:26 Final Mission
32:10 Ending