This pretty much hits the nail on the head. To even be capable of trying to balance this, the item would have to be consumable. Allowing players the ability to indefinitely see the IVs of wild spawns is simply not good long term.
Better an event be delayed or cancelled for a major bug than for it to be released in a buggy state.
While both are frustrating, the amount of backlash that the devs would face for releasing a bugged event would be greater than the number of players disappointed in an event being delayed.
The encounter with Zekrom is part of your initial run through the Elite 4.
Once you beat the last Elite 4 member you should enter a cutscene when you enter Alder's chamber that shows N having beaten Alder.
There is some dialog between them before N's Castle pops up around the Elite 4. You then have to go through some stuff in there before you encounter Zekrom.
If you have already beaten N and Ghetsis in the Elite 4 then Zekrom is lounging in your room eating all your pizza rolls.
A few ways to handle that are to either have it laid out like the GTL where the statistics are paged, or they can have a minimum usage score required before a move will show up in the statistics. Perhaps a combination of both would work, though infinite scrolling can be an option if it is viable in this context.