Seems like you're somewhat new to predator fish haha. Basically, ambush hunters don't know when the next meal is coming, so they take every chance they get. This includes lionfishes, scorpions, and anglers/frogfishes. Even if it won't fit, they might still try.
Triggers and puffers are better for communities because they can eat similarly sized foods to larger tangs and angels. That being said, you have to account for trigger aggression, which is based on the species as well as the individual.
If you're new to puffers, they need hard shelled foods as the majority of their diet. Puffer teeth grow continuously throughout their life, so if they don't have foods that make them grind them down, then they overgrow which can lead to the puffer not being able to eat anymore. Puffer dentistry is possible, but generally it's not fun for either party and can be deadly to the fish if you don't know what you're doing.