Ages ago there were three pets in the game and you got them all around the same time. None of them had any advantages or disadvantages over the others, to avoid making it seem like you chose a 'bad' pet to level. You could fish, or more realistically, forcefeed them hundreds of potions to level them up. And while the maximum level of them was infinite, it was said that that was temporary to give people something to do and the eventual cap was level 10. It's now 2020 and pets are in a really awkward state. You can get your first pet in under an hour into the game. You can get your (current) last pet in about 20-30 hours+ (if you're doing a ton of side content) in an optional area. The only real change between 2014~ pets and 2020 pets is that pets now get forcefed actual food from Oak instead of potions. Despite trying to keep things 'fair' between all pets, this makes Slime and Rabby by default the 'best' pets. You've been investing into them for the longest time, switching to later game pets throws aside all your past progress and invests a ton more resources into them just to try and get back to the bonus you had with Slime and Rabby. That's not an ideal system. I feel like it would be best to treat pets as if they aren't all created equal, because that's a false equality. The problem shifts from "Why should I level my slime, the wisp is better!" to "Why should I level my wisp for no overall benefit, the slime has all my invested EXP!" Ways to solve this: Before anything else, give pets their level caps so there's an actual finality to them. Then any number of any of the below. 1. Make earlier pets level faster, but their max cap is lower. 2. Make later pets level faster than earlier ones. 3. Give every pet a unique max level bonus when equipped. Slime? +25 HP for maxing. Rabby? +3% crit. Wisp? +10 EP. 4. Give every pet a unique max level bonus that is awarded to you when that pet hits max level, without needing being equipped. Either in terms of stats, a unique housing item or a cosmetic hat. A gift from your pet or Oak for taking such good care of them. 5. Change how pets level. Levels 1-5 can be fed with pet food, 6-10 with fish. Alternatively add in a Pet EXP bar that fills as you keep a specific pet out while killing enemies, as a different way to level pets. You can invest this EXP into any specific stat, up to a certain level. But it is the slowest way. I can't think of anything else at the moment, but... pets are in a really awkward place right now. There has to be some way to improve upon it. A way that doesn't involve letting pets fight, given the can of worms and bugs that would involve.