I understand the frustration with Velociraptors and high damage dinos. I find it more of a pain when they’re several levels stronger than your team, and they’ve purposefully lost to dominate the low rank arenas (or they went nuts hunting and got their dinos stronger that way, but even so, leveling a dino isn’t easy as they get stronger). However, as a Velociraptor user myself, I’ve discovered there are not only decent counters (anything with good armor and/or a speed decreasing move works; Stegosaurus suggested), but also strategies to use the famous glass canon. My raptor can still easily go down to tougher dinos, but she has come through in tough spots, and I have the recordings to prove this. These battles take some strategizing, so you need to know how your team functions in order to succeed. Yeah, sometimes you get bad draws, but if you use them right, even if you lose, you’re still learning how they work with each other. I’m still learning which dinos to use, but I have a pretty stable team for Mt. Sibo until I start getting beaten again:
Dimetrodon can be a good starting dino as it is frail, but has really good attack as well as being immune to negative effects.
Aegetinosaurus, like Apatasaurus, is your best friend with its high health, speed lowering attack, and Rampage. It has actually one-shot a couple dinos, so if you see this guy, go for him.
Einiosaurus is a good defensive dino with stunning attacks. Stegosaurus is also like this, but comes with the speed-reducing Thagomizer, making it good for countering raptors.
Suchomimus takes a bit more strategy to use, but its Wounding Strike comes in handy and has helped gain victories in the past. Gorgosaurus is like this as well, but comes packing Ferocious Strike, as well as armor and shield piercing attacks.
Velociraptor is still a glass canon and should be treated with respect. Bring it in only when needed. Starting with it I’m kind of against 'cause while it is a “smart” move, it really isn’t. Also, raptor starters are just trying to sweep.
Finally, if you see any kind of Ankylasaur like Euo, go for it. It may not have the greatest strength, but this thing is a great defensive tank. She’s actually come through very well.
Learn how your team works, build it around what appears in your area (a trick that’s working for me), and make them strong.