What do you recommend? I want two clowns but the other 3 I’m flexible on.
I would consider starting a thread asking for something like "Help with stocking list for Fluval 13", I think you'd get a lot of replies, and you would be getting more than just my advice, which I'd always suggest
And, I would always research or ask here at R2R before purchasing any livestock, don't just believe what the worker at the fish store tells you!
My honest thoughts - and in no way am I trying to be a downer - is that a pair of Clowns are really best for 15 and ideally 20+ gallon tanks. Clowfish do get quite big and they are stocky, and they are definitely aggressive and need their own space. That said, many, many people keep a pair of Clowns in 10+ gallons, so if you really want Clownfish, you could do it, just be aware that Clownfish are definitely aggressive (more so when they get bigger), and may not tolerate any other fish in "their" home.
Similarly, both Damsels and Royal Grammas are typically suggested for tanks 30 gallons and up. Although small, Damsels can be terrors. Royal Grammas range, some are quite peaceful, but they all have the potential to be aggressive.
Have you seen a Goby fish/Pistol Shrimp combo pair? This is a fish and shrimp that live together, and make a really awesome display in a smaller tank.
I would look for fish like small gobies and bennies, maybe a fire fish. Here's some posts on R2R that may help:
https://www.reef2reef.com/threads/fluval-evo-13-5-stocking.900688/https://www.reef2reef.com/threads/stocking-ideas-for-evo-13-5-gallon.983488/https://www.reef2reef.com/threads/fluval-13-5-stocking-ideas.937463/
Here's a list from another forum with some stocking ideas based on tank size that might help:
https://www.nano-reef.com/forums/topic/74703-lgreens-ultimate-guide-to-nano-fish/
And, I would encourage you to look into some invertebrates. Your Fluval kit has a light than can support many easy to care for corals. There's also a lot of cool shrimp, crabs, hermits and other inverts that again are really great in a small tank. Many little animals that would get lost in bigger tanks can be the stars of the show in a smaller tank.
I hope this helps; let us know if you have further questions or need further stocking ideas!
