As far as I know, Pardons cannot be reversed. The damage he is going to do scares me.
Executive orders can be dealt with by Congress but the President can still veto it.
Courts can overturn an executive order.
Carter pardoned the draft dodger vote. And we’ve seen out-going governors commute all death sentences.
But this is too legalistic.
Presidents can be ignored if enough people want to ignore him and things patched up later with some formula like declaring him retroactively incompetent.