Since, this game is on PS1. Can, it also be on PS2? Or, is it only on PS1? I am just making sure. Cause, I feel like that I want to Speedrun this game sometime in the future.

You can play it on PS2 since all of the individual levels are timed with ingame time, as for full game runs... im not sure. Shouldnt matter too much, the more people on the leaderboard the better.