Medals are prizes for protecting the SealStone well, and are awarded alongside crystals or EXP bonuses. Each medal can only be earned once per stage, resulting in totals of up to 20 crystals and 3,000 EXP per level. Although it's not possible to earn all medals for a given stage in a single attempt, multiple medals can be gained in one attempt, and the others can be gained as well during later attempts.
Gathering all medals across the ten stages in an area grants an additional 52 crystals (which don't show up on the stage results screen when you accomplish it) - 10 for HP1s, 8 for Golds, 6 for Silvers, 4 for Bronzes, and 24 for Special Medals (the last of which come with "Special Master" GameCenter achievements). Hence there is a theoretical maximum of 2,520 crystals to be gained by gathering those medals across the 10 areas and 100 stages (plus 60,000 EXP for the EX medals, which are only available in the first two areas).
You can see which medals you've achieved above the image of each stage. The "Medal's info" (sic) button can be used to view the prerequisites, which vary for each level.
List of Medals
Special (SP) Medal
SealStone HP must be full (20 points) at the end of the stage. Only certain witches of up to a certain level may be used - typically you may use what you had when the stage first became available, plus any witches unlocked with crystals. Use the "Medal's info" button next to the stage icon to see which are eligible.
Use of "full power" orbs, the Mighty Witches power up, Heal All or Kala's "Stop the Clock" ability will prevent this medal from unlocking. On the other hand, Daisy (super) (unlocked via Bingo) will not prevent it (despite never being pictured as "allowed") (the exception is if the stage limits Daisy's upgrade level to two, and you upgrade her to MAX instead), and nor will rewinds.
Award: 6 crystals per stage, plus 24 when gathered from all stages in an area (84 per zone, 840 maximum).
Gold (G/P) Medal
SealStone HP must be full (20 points) at the end of the stage.
Award: 4 crystals per stage, plus 8 when gathered from all stages in an area (48 per zone, 480 maximum).
Silver (S) Medal
SealStone HP must be at least 15 points at the end of the stage.
Award: 3 crystals per stage, plus 6 when gathered from all stages in an area (36 per zone, 360 maximum).
Bronze (B) Medal
SealStone HP must be at least 10 points at the end of the stage.
Award: 2 crystals per stage, plus 4 when gathered from all stages in an area (24 per zone, 240 maximum).
SealStone HP must be exactly 1 point at the end of the stage. Obviously this cannot be achieved in the same attempt as the other medals listed above.
An easy tactic for achieving this medal is to unlock the earlier medals (to ensure you know how to play without allowing the SealStone to be damaged), then when you next enter the stage, simply lose while holding a Flare ticket in reserve (which you should then activate). Flare will restore the SealStone to exactly 1 HP, destroy all enemies remaining in the field, and grant you the MP for their demise (which you should promptly spend to ensure nothing further gets through).
An alternative, cheaper method is to use Blue magical flower to distract your witches from attacking at the right timing to bring down the HP of the SealStone to exactly where you need it.
Award: 5 crystals per stage, plus 10 when gathered from all stages in an area (60 per zone, 600 maximum).
Extra (EX#) Medals
The final three medals have varying requirements per level (use the "Medal's info" button next to the stage icon to see them), but provide 600 EXP for the first, 1,000 EXP for the second, and 1,400 EXP for the third (Stages 3-3, 3-5, 3-6 and 3-9 reward you with 30, 50 and 80 crystals, for each EX1, EX2 and EX3 medal, respectively). These are only available in the first three areas and may have the following objectives:
- Summon Lv X character in stage!: Just summon said character with level equal or above the asked. For some reason, Super Ordinary Daisy do not complete the "Summon Lv X Daisy in stage!".
- Use orbs X or more in stage!: Use an amount equal or higher of orbs than the asked. They must be used in a single run. Most of these medals will require a lot of leveling to get the amount of orbs needed.
- Get X treasure boxes in stage!: Treasure boxes drop rate raise drastically when you use Fullpower on a character, so your best strategy would be using Fullpower I (to get more Fullpower time, instead of more power) in a single character, using Sarah to enhance her attack. (If it's a stage with both land and flying enemies, you'd then activate Nicola's Fullpower I too). You need the specified ammount of Treasure Chests in a single run and both Red Treasure Chests and Wood Treasure chests counts.
- Summon Character, and use Fullpower X!: Just summon the character, at any level, and use the specified Fullpower. (Which would make you need to have the character at a minimum level for Fullpower II, for example.)
- Clear stage result HP X!: Complete the stage with the Sealstone with that exact amount of HP. It's better to let the first enemies have clear path to the Sealstone until the desired HP, then avoid taking any damage from then on, since they are easier to count and to kill.
- At X points or more!: Achieve the specified amount of points at the end of the stage. Bonus like the "No Release Bonus" and "Perfect Bonus" also counts. Your best option is to get 3 Blue magical flowers as soon as possible then have a Fullpower Daisy hit them to their highest level.
- Character 1 and Character 2, use Fullpower X at the same time!: Have both specified characters have Fullpower active at the same time. Again, it requires a minimum character level to use the specified Fullpower level.
- Get X red-treasure boxes in stage!: Applies the same rules and strategy of "Get X treasure boxes in stage!", but instead you will need the red (rare) treasure boxes. Wood (common) treasure boxes do not count.
- Get X wood-treasure boxes in stage!: Applies the same rules and strategy of "Get X treasure boxes in stage!", but instead you will need the wood (common) treasure boxes. Red (rare) treasure boxes do not count.