In Palworld a Dungeon Alpha Pal will appear at the end of each Dungeon, accompanied by two or three Pals of the same species. You can reroll these Dungeon bosses by leaving the room, going down the previous hall, and returning.
Following this method, you can easily reroll the appearance of various Alpha Pal species (up to 18 different species) in the boss room. You can catch the smaller Pals, leave the room and return to reroll the Alpha, and new minions will spawn along with the new Alpha!
This method is convenient since you do not need to travel a lot. When farming these bosses, always make sure to keep an eye out on your resources and health, as well as your Pals.