PSO2 is great with this though.

The first free-mode forest always has a Rockbear as the final boss. But once in a while it is replaced by a Rogbelt, who is a little bit bigger and tougher with a diffirent move set and better gear.

But the thing i would like most is, very very rarely after beating a dungeon in PSO2, a second teleporter will appear and takes you to a mysterious island. I've gotten an island with nothing but Frog Rappies (all dropping cool loot) before, but there's supposed to also be some rare bosses and things appearing once in a blue moon.

There's also a tournament where people have to kill a number of monsters and/or clear a dungeon in the fastest time. and you see what times people put down to beat. The top ranks get some nice rewards once it finishes i believe.