I agree entirely, Mario should be nerfed, definitely, I wouldn't completely remove it as its a classic kit, and still quite cool in some ways, or could be at least. In my opinion, there are many other kits that need altering of coins and power levels (e.g. Fighter needs to have strength 2 back to be worth 4000 coins) but Mario in particular is the most annoying. Yes, you can run away from Mario as they cant enderpearl and have the jump boost that makes then jump slower. However, pvp is about fighting other players, not running away from certain kits and fighting others, and you realistically cant kill marios with pure pvp skills alone, you either need to be lucky, have a teammate to help you or you are very, very skilled and the Mario doesn't use their pots, which are a 2 direct-hit kill and the God apple, which makes them for a good while, almost invincible. But, instead of moaning constantly, I will make a structured suggestion for how it can be balanced.
1. Give the kit protection 2 instead of protection 4, a kit costing 2000 coins and having a jump boost should not have maxed out armor, especially as in most actual Mario games, Mario in most games dies in 1 hit, so less armor is my simple solution to this.
2. Make the mushroom sharpness 5 instead of 7, or however OP it is. Considering that only a few kits have more power in hits than it does, and a kit that cost the same amount as it does, Rider, does 7 hp of damage instead of 8.75 and has less armor (Way less), so it should do less damage, the fire damage is fine as its not to much of a problem, as water is available in every map.
3. (BY FAR THE MOST ANNOYING THING ABOUT THE KIT). For gods sake do something about the pots. Since no kits are resistant to pots, and no, armor doesn't affect how much pot damage does, Mario can 4-3, and sometimes 2 hit players. This is ridiculously powerful, as in a group of people fighting, whatever the kit, Mario can use its jump to sail over the fight, and spam a load of pots on the fight, killing everyone and spoiling the fun, and getting the Mario a load of kills using almost no skill. My suggestion here would not to nerf the damage, and do something more productive with it. In scbb the creeper has a second or 2 gap in-between when it can throw pots, so it doesn't make the kit unfairly powerful to low jumping kits. This was something myself and Zain came up with for the same problem as Mario has now, so if this was added to pvp, the pots would still be powerful, but would balance the kit and make the Mario user have to use some timing when they threw their pots.
4. Simply get rid of the God apple. Considering you can soup as well as this in pvp, the God apple only makes it so you don't have to soup at first (Or die) and when the regen wears off, you don't have to soup so much as the resistance will block out most of the hits, and since pvp isn't like it used to be, where the apple was needed as many of the other coin kits had gapples to keep them alive as soup refills weren't a thing back then, having one now where the other kits don't doesn't give the kit much point having it anymore.
Those are my suggestions. I would also like to thank Saword for bringing this up, I was going to bring it up soon myself as I as getting frustrated about it, but as you brought it up, I no longer need to, so thanks.