So you've bested the Westfall tamer and your pets are now level 4. However, you've flown out to Redridge and you now see this Darling Child with her level 5 bunnies. The conundrum: do I kill her pets now (they're only rabbits, right) or do I wait until I'm level 5? They're all Critters, so it depends on how many Beast pets you have and how many Elementals or Undead you don't have.
If you've got two or more Beasts, go for it! If you've got one Beast think about it (I managed to do it, but it took three times and I lost one pet). Otherwise, you should probably level them first. Fortunately, there are lots of buzzards behind Lakeshire and a ton of rabbits living along the Lakeridge Highway. Get a few kills each and your pet crew should be level 5.
So there's this kid with too much time on her hands. She's stuck in this weird little town that takes 5 years to get a bridge built. What does she do with her spare time? Why she raises lots and lots of vicious little bunnies! We need to control the rabbit population and I'm going to show you how!
Dipsy is a Critter. That means Beast abilities will do extra damage to him and Elemental abilities will do less damage. It also means Humanoids take less damage and Undead pets take more so be extra careful if you have an Undead pet. The bad news for you is, they're all Critters so you can't pick your battles as easily as you can with other trainers. The good news, if you have a Beast, is that you should be able to take one and almost two of these guys out with just the Beast.
Dipsy has an ability called Flurry. This ability hits a few times for moderate damage, but hits an extra time if Dipsy is faster than you and attacks first. If you can slow Dipsy down a bit, go for it, otherwise, you just have to hit Dipsy as hard as you can and he'll go off to Bunny heaven.
Flipsy is kind of annoying. She has two abilities that can hurt you: Stampede which is just like Flock only with a herd of rabbits, and Dodge which lets Flipsy avoid your attack for 1 full turn, or more if she is faster than you. This means you have to time any hard hitting abilities carefully and also be prepared to swap if you get the +100% damage debuff on you.
Flufftail is a bit less annoying than Flipsy. In addition to having Flurry which hits harder if he is faster than you, Flufftail also has Burrow. Burrow allows the pet to hide underground for a turn avoiding your attacks and then jump up and hit you extra hard with Beast damage. This means you have to time your attacks a bit and also swap your Critter pets away when Flufftail burrows. You will see abilities like Burrow alot from tamers.
In conclusion, this fight can be very annoying if you don't match up well against Critter pets. Even if you do match up okay, you still have to pay attention to the abilities. It may take you a few tries, but it's good practice.