After the release of Outrage MAX, Takara Tomy changed rules regarding how races sharing a common part are handled. As most of us OCG duelists know, Outrage MAX, Beast Folk Go, Gel Fish and even Giant Insect are these kind of races. I actually wasn't aware of the connection between Giant Insect and Giant races since in TCG they were handled as totally separate races, but it makes sense.

My question is, since this rule change is post-TCG, does it mean it doesn't apply to TCG format and thus wouldn't change how Petrova affects cards? This would be logical but unlikely there is a single correct answer for this.

I think that the logical answer would be "Yes, it doesn't apply to TCG format". Similarly, if I have a Mongrel Man and destroy my opponent's Aqua Soldier, I don't get to draw a card (the fact that destroying counts for effects such as Mongrel Man's also comes from the post-TCG ruling).

I believe it should work like this because, technically, TCG is a vintage format. It only uses cards from a certain (CLOSED) period and therefore it should also utilise rules from that period.

Another argument could be that TCG rules were different from the beginning (more than 40 cards allowed) and any changes to OCG rules should not impact TCG rules at all.

Great arguments and it's true that TCG should be handled as vintage format since it clearly is one.

I didn't even know that in OCG you get to draw cards with the effect of Mongrel Man / Super Trash Train Fuuma Devil even if the destruction would be substituted. Doesn't really make any sense and the wiki still states the following on both Mongrel Man's and Super Trash Train Fuuma Devil's Rulings page:

Q: When Mighty Shouter is destroyed, does this creature let me draw a card?
A: No. Mighty Shouter isn't actually destroyed. When it loses a battle or an effect would otherwise destroy it, Mighty Shouter is put into its owner's mana zone instead of being destroyed. Since Mighty Shouter isn't destroyed, Super Trash Train, Fuuma Devil doesn't let you draw a card. The same is true for other cards that are not put into the graveyard when they are destroyed such as Aqua Knight and Ouks, Vizier of Restoration.

The problem with Wiki is that it's internally inconsistent, mainly because of rule changes (and no change to rulings affected by this change) or simple mistakes. To me it was a surprise to learn that "instead" effect would negate the effect such as "when another creature is destroyed".

I'll need to dig around in order to find the page that says about rules change. Sadly, there is no list of rule changes and my Japanese isn't good enough to roam the official Takara page.

Never mind, I might have been wrong about one (too many exams, my brain hurts lol). I probably confused with with the effect such as that of Deadly Love: even if the creature you destroy is not actually destroyed because of "Instead", you still get to destroy an opponent's creature.

It's okay, the main thing is that it's clear now. Rues can be confusing.