I'm making a tas and 2 piranha plants are in my way that I've never seen in any run. Is it framerules or RNG?

It is very likely because the TAS plays the level differently than in your runs. You probably despawned the plants in your RTA attempts, but the TAS does the stage differently than how you played so the plants were there like normal.

Things despawn because there are too many things on screen, afaik RNG and framerules have nothing to do with despawning. Also I think Mars02 is right.

this might be incorrect but i'm pretty sure every single pipe is programmed to have a piranha plant in it, with the exception of 1-1.

so if there's no piranha, you despawned it in your RTAs and just need to implement that into your TASes

Yes, every pipe in the game with the exception of 1-1 should have a piranha plant in it. You despawn them by playing the level a certain way/hitting enemies to make different patterns, etc.

Alright thanks.

Most of the time its not a problem but in 4-2 and 8-4 its been a problem

In 4-2 if it's the pipe which you go down for the wrong warp, hit the vine block to despawn it.

in 8-4 second room if you land on a buzzy beetle it will spawn the plant in the pipe you need to go in

Thanks

So I would assume bullet bill's work the same way

idk, i would also assume so tho

I think that does have to do with frame rules, but I'm not 100% sure. I do think I saw someone say it is, so I'm like 99% sure, but idk.

Ok

Bullet bills depend on what framerule you arrive in the level, how fast you get through the level, what enemies you bop etc.

Noice