Pet leveling trick (not that awesome as before)

First of all, this ain't even close to the XP you could get while the XP vial was bugged, but it gives decent XP and imo you can bot this.

Also this leveling can be done on/with any pets, they all give the same amount of XP but I found out this to be best one cause of the type of the pets.
I leveled my rogue from lv85 all the way to lv90 using only this method.

What do you need:
Curious Wolvar Pup / Kun-Lai Runt
I suggest you to get one Wolvar and two Runts or just get three Runts

Who do you kill/defeat:
Lucky Yi Critter legendary pet

Why this pet:
Yi is a critter, using only one critter attack, also he takes more damage from beast attacks and deals less damage to humanoids.
Wolvar/Runt are humanoids who deal beast damage. Put two and two together.

Math time:
At level 87 you get 134'200 XP per one win. To ding lv88 you need 18'980'000 XP. That means you need to defeat the pet 142 times. One try took me less than 2 mins.
So it's gonna take you 284 mins. That's 4 hours and 42 mins.
Personaly, I managed to duke the pet a bit quicker.

Bonus:
Kill the critters around Yi, they also give decent experience, and if you get lucky and face three critters, you actually get better XP/hour than defeating Yi.

Last words:
I know there are much better methods (cage masters, money runs, etc) but this is soloable, and I'm pretty sure botable.