Defeat the bosses on water island to have a chance to discover Legendary stones that allow you to summon the Legendary Monster on Water Island. Rarity of the stones increases after acquiring some. It is common for the first 3 stones to come quickly and the 4th soon after. The 5th reportedly takes a long time to get, potentially requiring lots of time or minocredits to get.
Further improve your favorite monsters by making their skills more powerful. At the cost of star coins. High level attacks cost more to upgrade. The number of ranks appears to be based on the mino's rarity as follows: common = 2, rare = 3, mega rare/legendary = 4*. The first legendary encountered only had 2 ranks. After several days and an update to 3.0.1, the ranks now show 4.
Collect blue star coins from defeating monsters in battle to buy levels, skills, perks, and more monsters via the mino book. Star coins are the equivalent of XP-stars in "old" MinoMonsters. Because star coins can be used for the above, you no longer automatically get attacks/perks when leveling up.
All monsters can be found in the wild. Once you find a monster and defeat it, you are able to use blue star coins to unlock it in the Mino viewer and make it join your party.
Monsters now have maximum levels based on what Island they are found on and what rarity they are. Note that Minos that have already been leveled higher than the new max level before updating the app will still keep their higher level. You can level up a mino beyond their individual max level by spending mino credits. When spending mino credits in this way, they go up by 2 for each level. For example, from 33 to 34 costs 48 credits. From 34 to 35 costs 50 credits.
You can also purchase star coins with minocredits when leveling a mino or upgrading their stats. The conversion ratio is pretty bad though as it depends on the normal amount of star coins you require (616 credits to by the stars required to get highest rank on the maximum attack for some minos has been seen assuming no star coins to start with). This can result in buying a level from 34 to 35 costing 500+ minocredits.
Removed Stat Choices
You no longer choose to increase Attack, Defense, or Element when you level up. Old minos had their stats reverted (at least for the starters). All the starters appear to finish with the exact same stats (700, 700, 700) at level 35.
Candy can no longer be collected or spent to heal your monster or catch monsters. Healing during battle now requires green MinoCredits. Cost is 1 minocredit for a full heal in battle. The full heal only appears to work once per mino, after that it reverts to healing like the candy use to heal at the cost of 1 credit each time. You can also speed up the active mino heal on the home screen by spending 2 credits.
Opening the mystery chest gives you Star Coins (via gunk stone roughly adding 3000 coins), Legendary Stones or adds a Mino to your team. Your first treasure chest is free, subsequent ones cost green MinoCredits. It is currently unknown if the free Mystery Chest is recurring (ex. weekly) or one-time-only. This is how you can get the other two starting minos if you have the credits to spend. This also represents the only way you can get multiple minos of the same type (assuming you did not have them already from version 2.0). The mino gained is random and immediate goes to your team selection screen.