Here are some of my ideas:
1) Epic spawners should spawn other variants of mobs then their normal spawner.
For example:
an epic creeper spawner spawns charged creepers
an epic sheep spawners spawns rainbow sheeps
a normal villager spawner spawns baby villagers and an epic villager spawner spawns normal villagers
a normal pig spawner spawns baby pigs and an epic pig spawner spawns normal pigs
....
2) No more merging!
Here's an idea of how you can easily see if people merged. So when a player buys a spawner, then the spawner should be named for example "[player]'s pig spawner" or it should be visible in the spawner interface, this way staff (and other players) can easily get proof if someone merged.
3) Change Custom Crops
Right now, the custom crops don't give you much money. A cool idea would be that you can upgrade custom crop seeds. For example, you can upgrade (with xp or mobcoins) the growth speed or amount of money they can give. Another useful feature would be that you don't have to replace the crops after you harvested it.
There's also an annoying bug where you sometimes plant a normal seed instead of the custom crop seed.
4) Pets
Another random idea is that Skygod's can spawn in pets. You can already spawn in pets with some bones/fish/apples but they can't move or do anything and after some time they despawn. It would be cool if they can actually move and do stuff without despawning every minute. There should be a command where you can choose out of a dog, cat or horse + its name.
This is all I have now, Thanks for reading.