I just found Pokemon FireRed's equivalents to MissingNo

In an emulator use 83007CEE 0000 and walk in a patch of grass to find a black circle with a question mark. For the second one instead, which is a bunch of question marks, use something like 115 idk i only knew it ended with a 5. As the last one try doing the Hydro Pump TM in the PC cheat code and you'll find a crap ton of question marks