Hello, I've been interested in learning to speedrun this game but currently I will only be able to play on an emulator. Is there a specific one I should/can use? Thank you

Only one that is currently allowed is PCSX2 with these versions: 1.4.0, 1.5.0 or 1.6.0.

You can find out all you need in the "Game Rules" part when you click on "View rules" button.

thank you!

one last question, Where is a good place to find the iso i should use

Since its pirating, I cannot link you. Try and ask the emulator runners in discord

Linking and sharing ISO is piracy, however if you have the PS2 disc and a disc drive on your PC, you can play the game directly by the disc by choosing Plugin in the CDVD menu. You can also rip the ISO using a program such as ImgBurn to create a .ISO file from disc.