>completing an insane hunt
It already gives a reward upon completing it. (/hunt and right click the Insane hunt dye to check possible rewards)
>getting a certain lvl in the mcmmo
Skill crates + passive skill buffs (/skills)
>catch shiny, or legendary pokemon,
Shiny & Legendary hunter quests, besides the Pokémon itself
>voting
You already get keys, tokens, and claim blocks by voting, as well as /streaks, so you're already rewarded.
Maybe the valid point would be the mega stones, which there's the Mega Hunter quest, but I'm unsure on its requirements & rewards too.
Overall most of those are already a thing, if you want an improvement on those you could suggest what you'd like to see.
