If we consider Buddha (rather, in the Zen version) a deity, then he would, of course, be stronger than everyone else.
Firstly, because even if the other gods had cheating abilities like immortality, they would not be able to understand that victory does not carry value in itself, but is only an integral part of a single whole, capable of forming harmony only in combination with defeat. However, coming, or even approaching such a realization, will not be available to all players, so most will play without even realizing that Buddha actually wins all battles - even those in which he does not participate.
And secondly, because even if the player does not reach enlightenment during the game, sooner or later he will have to put down the joystick and turn off the console. In other words, one day he will leave the world of the game, which without any stretch can be associated with the exit from Samsara. This moment will mark the final and inevitable victory of the Buddha.
It is impossible to arrange a fighting game between Gods of different religions for two reasons:
God, by definition, is always the strongest and no one is equal to him.
He is one, just different peoples give him different names and different scriptures describe his different qualities. Therefore, he will not be able to fight with himself. it doesn't make sense.
But if you arrange a fighting game between demigods (such powerful living beings, usually they control different elements) Indra type in Hinduism (analogue of Zeus), Vayu - the God of the wind, Yamaraj - the God of death, Shiva, etc. ... It will be a gorgeous sight. The ancient scriptures of India recount these battles in abundance. Well, now there is a gorgeous film adaptation of the epic Mahabharata, where demigods incarnated on earth staged a battle. According to the Mahabharata, the most powerful demigod is Brahma, the creator of the universe, Shiva is a very versatile person, and Vayu is the God of the wind.
The whole point of fighting is in the game balance. Any character must be able to defeat any other character. What is the point of creating a conventional game "Pantheon", where the conventional Jesus is obviously stronger than everyone, because he is immortal?
In general, such a fighting game exists and it is called Smite :)
Ideally, the strongest would not be, because otherwise the game balance is upset and the game simply loses its meaning. But if you're so curious, you can head over to the Smythe forums and read which god the players complain about the most.