Scouting monsters is your primary method of expanding your team, but it's not always guaranteed. To maximize your scouting success rate, several factors come into play. Firstly, weaken the target monster as much as possible without defeating it. The lower its HP, the higher your chances. Secondly, use Monster Treats. Stronger treats (e.g., Sirloin, Prime Rib) significantly boost your success rate. You can feed multiple treats to a single monster before attempting to scout.
Thirdly, your monster's Attack stat plays a crucial role. Monsters with higher Attack will have a better chance of successfully scouting. Consider bringing a dedicated 'scouting' monster with high Attack and perhaps a skill like 'Scout's Honour' if available. Finally, some monsters have innate resistances to scouting, making them harder to recruit. If a monster consistently resists, try leveling up your scouting monster or using even stronger treats. Don't give up on rare monsters; persistence and proper preparation are key to a full Monsterpedia.