We've had these same issues for years now, everything just cycles through and eventually re-stabilizes.
How? The average player stays on an MC server for 3 weeks. So, every 3 weeks essentially a large chunk of Pokemon, items, and whatnot come out of circulation. The server essentially fixes itself every 30 days, but often times takes a bit more time for noticeable effects, say 60 days.
There is an exception to this rule- Holidays and Summer break, and that's where we are now. Those old players that have quit months ago, come back because they're out of school. So an influx of more goods are re-introduced to the market.
While we certainly don't have the best economy, we're doing the best we can with what we have currently. As stated above, the major issue is the long term players that are sitting on hundreds of millions in cash. While I am not saying they are at fault, that's where the issue resides. Again, they are in no way at fault- it's just they don't have anything to spend that cash on. We've had meetings on this in the past but we can't figure out what someone would be willing to pay 100+ million for. It's a tough situation. Could we potentially offer commands like /fly for large chunks of money? Yes, but that wouldn't work seeing as those players are often times Arceus holders.
One way some of the other larger servers handle such market inflation is the held items. Many have all recipes disabled, so the only way to obtain them is what they set in place- whether that be in shop for crazy amounts, or crate only and let the players set the prices in auctions. Seeing as there are hundreds of held items that are easily obtainable, those hundreds of items could become rare goods and all sell for 50k - 200k. I preferred it this way but when we held a vote on it, the majority of votes said to keep recipes.
We just need some new and unique ideas to keep those long time players spending more of their in-game cash.
Basically the market recovers from everything that we tossed in crates after about 60 days, and then the cycle repeats. Unfortunately, when we nerf crates, we just don't make any money, and money is what keeps us up and going realistically. I not only am paying for server development, but also the mod. It was a different story back in the day, but now we basically have part ownership in the mod and that comes with it's own set of costs to keep up.
One idea that comes to mind is potentially adding Totem Pokemon with unique particle effects and some extra buffs like in the game, and allow them to be catchable. Those could sell for a massive chunk if we kept the spawn rates low, and don't add them to crates. Then there would be the balancing issue- some may complain if we allow those OP pokemon to participate in tournaments, even if their stats were like 20% higher than the standard version of said Pokemon. If they can't participate in tourneys, then what's the point in owning them.
Balancing is very difficult and I'd like to say for what we have at our disposal, we're doing decent. Obviously not amazing, but decent. We're all for ideas we just need a home runner idea and we'll be substantially better going forward