Timey's Medal List

Alright, I've been meaning to make this list for a while, so here goes nothing. Just let me know if any of these medals sound  useful to you, and I'll be perfectly happy to swap them out. I'll just group them by attack type (single and all) for now, though I might reorganize if it gets confusing. I may also add more as time goes on.

Group Attack Medals
Stained Glass #5 [EX+]: Tier 8, upright speed, Unguilted, Second Chance III, STR +1000 (x2), Damage in Raids +40%
Deals 6 hits, 1 turn ↑ STR & U-STR & S-STR by 7, ↓ targets' DEF by 4, S-DEF by 7. SP ATK bonus +40%. Inflicts more damage the lower the slot number.

HD Larxene: Tier 6, reverse speed, 175% Guilt, ATK B III Max & SP GA 1, Extra Attack: 40% Power, Max Gauges +2, STR +1000
Deals 3 hits. Lowers targets' DEF by 3 tiers for 1 attack. Inflicts more damage the more gauges used this turn.

HD Ava [EX]: Tier 7, upright magic, 200% Guilt, Defense Boost IV, [no traits]
2 turns: ↑ PSM-DEF by 2, ↓ targets' DEF by 2 & PSM-DEF by 7 tiers. Inflicts more damage with 1 enemy left (incl. raid boss). Enemy countdown unaffected.

HD Terra [EX]: Tier 7, upright power, 200% Guilt, ATK B V & GA 1, [no traits]
Deals 4 hits: 1 turn: SP ATK bonus +30%. Inflicts more damage with 1 enemy left (incl. raid boss).

HD Gula [EX]: Tier 7, upright speed, 200% Guilt, ATK B V Max & Lux+, [no traits]
Deals 3 hits. 2 turns: ↑ S-STR by 7, ↓ targets' DEF by 2 & S-DEF by 7 tiers. Inflicts more damage with 1 enemy left (incl. raid boss). Enemy countdown unaffected.

Stained Glass #4 [EX+]: Tier 8, reverse power, 230% Guilt, ATK B III Max & AP+, DEF +2000 (x2)
Deals 6 hits, 1 turn ↑ STR & R-STR & P-STR by 7, ↓ targets' DEF by 4, P-DEF by 7. SP ATK bonus +40%. Inflicts more damage the lower the slot number.

HD Pete: Tier 7, reverse power, 200% Guilt, Poison, Damage in Raids +40%, Paralysis Resist 20%
Deals 4 hits. 1 turn: ↑ Reversed STR by 1, ↓ targets' DEF by 3 tiers. Inflicts more damage the higher the slot number.

HD Zexion: Tier 7, reverse magic, 173% Guilt, SP Attack Gauge 1, DEF +2000, Aerial Enemy DEF -60%
Deals 7 hits. For 2 turns: raises PSM-STR 4 tiers and PSM-DEF 2 tiers, lowers targets' STR and DEF 1 tier. Inflicts more damage the more gauges are full.


Single Attack Medals
Launchpad McQuack: Tier 7, upright power, 200% Guilt, ATK Boost II & Lux Plus, STR +1000, Max HP +800
3 attacks: ↑ STR & P-STR by 7, ↓ target's DEF by 7 tiers.

Huey, Dewey & Louie: Tier 7, upright speed, 200% Guilt, ATK Boost II & ATK Prize+, Max Gauges +2
3 attacks: ↑ STR & S-STR by 7, ↓ target's DEF by 7 tiers.

Scrooge McDuck: Tier 7, upright magic, 151% Guilt, Defense Boost 1, Ground Enemy DEF -60%
1 turn: ↑ U-STR by 2, STR & PSM-STR by 7, ↓ target's DEF & PSM-DEF by 7 tiers. Enemy countdown +5. Fills 7 gauges.

Webby Vanderquack: Tier 7, upright magic, 200% Guilt, Defense Boost 1, Max Gauges +2, Damage in Raids +40%
3 attacks: ↑ STR & M-STR by 7, ↓ target's DEF by 7 tiers.

I would say that the most useful medals listed here are:

Stained Glass #5 for upright and speed keyblades, Stained Glass #4 for reverse and power keyblades, and Scrooge McDuck for enemy countdown increase and gauge refilling.

Overall I would say Stained Glass #5 is the best to share at the moment for general use.