OK, I'm guessing you're new to the pet raising game.
Pets have stats, and pets have talents
Once you've maxed your stats(Str, Agil, Int...etc) your pet still gains the exp from training and from eating the snack after. It shows as 0 on the stat side, as these stats are already maxed, but if yuou look in the experience bar, it shows the game points, and the snack points gained.
This is how we all get to mega, by continuing to train after the stats are maxed.
I've been facing the same problem until one of my friends came up with a legit solution. Since he's a warlord he has been getting arena ticket snacks from the vendor close to the Cannon game. Most of them don't help out much (unless you want a higher resist), but,if you have a higher lvl friend, you might wanna consider doing short dungeons you can teleport into. The trial of spheres is what I've been doing for the past few weeks and I've gotten some legit snacks. I also have noticed an easy way to win in Grumpy Gobblers. Point the cannon all the way down then put the power all the way up. Change the essence to fire, and aim for a red block. I usually finish up the level in less than five tries.
Hope all goes well (If this doesn't help, try asking your friends if they have any tips for you)
Maxed stats have nothing to do with the level of the pet. Regardless of whether you have 100 agility or 300 agility, level is experience, not the stat. You still get all the same experience from training and snacks after stats are maxed out.
Even though your stats are maxed out, your pet still gains experience up to 2000. When you get to 2000, your pet will get a new talent and if it's something like Health Gift or Spell Proof, it will be at the max level as soon as you get it.
I got my teen to epic in less than a hour. It's not that time consuming if you have enough crowns. If you are willing to spend the money, here's how you do it…. 1. Look in the crowns shop for the mega pet snack and buy it. 2. Go to a game in the Pet Pavilion. (I suggest the Dance game because it takes the least amount of time) 3. Play the game, and feed your pet one of the mega snacks you just bought. 4. Play the game until either you run out of mega pet snacks (or energy) -When you run out of mega snacks or energy, buy more snacks or use the energy elixir
Just continue this method and you can train your pet to mega, in a very short amount of time!