[Pokemon the First Movie] Would other legendaries have intervened to stop Mewtwo?

If Ash hadn't changed Mewtwo's mind, and Mewtwo went ahead with destroying humanity and taking over the world - would other legendaries have done something to stop it?

For example: Would Arceus want to stop Mewtwo from destroying part of its creation? Would Rayquaza get upset about Mewtwo messing with the weather? If Deoxys landed (since there are no humans to stop the meteor), would it want to fight Mewtwo? Would Celebi, Manaphy, and Phione have done something to protect the forests and seas from Mewtwo's storm?

I don't know very much beyond gen 4, but are there legendaries that would be impacted enough by Mewtwo's plan that they would try to stop it?

(I know these Pokemon didn't exist at the time IRL, but presumably they did exist in-universe)