>>45736705Any shiny "easily" obtained by a player farming at home, yes. They're the lowest on the totem pole of valuable Pokemon.
>>45738071Thing is, though, WISHMKR Jirachi is still obtainable today. Anyone with sufficient time and autism could obtain a shiny Jirachi from that disc. Even with the entry cost of actually purchasing a colosseum bonus disc, it's still obtainable while those random and obscure events are not. At the end of the day, scarcity decides what an individual Pokemon's value will be, which is why event Pokemon from events from generations ago command a high value among traders.
Don't get me wrong, with proof a shiny WISHMKR Jirachi still holds good value. But the fact that it's still obtainable and that there are a small handful of documented spreads that shiny can have mean it's not going to be as valuable as you might want it to be. Though if you don't plan on trading it, it's kind of a moot point.
MYSTRY Mew is in an even worse place. IIRC someone actually dumped an untouched distribution cartridge and now every single possible PID/IV combination for that event is available online. Means unless you happened to take pics of yourself at that event, your MYSTRY Mew will always be under heavy scrutiny as it's perfectly simple to grab a clone from that dumped cart. Gen III events were janky as fuck.