Regular Equipment is fine for the story mode, but it can not compete with Souls in a competitive setting. Souls can give almost equal stat bonuses as top tier Equipment without any downsides. Additionally, Souls can provide unique and powerful effects. Yo-kai can be turned into Souls at the Temple of Viture. While some of these Souls alone can be very strong, such as the Soul Gauge replenishing Oranyan Soul, Souls themselves can be Fused together to make even stronger Souls. These Rare Souls can only be created with certain combinations of Souls, all of which are listed in this guide.
When using the Soulcery option to Level Up Souls, attempting to fuse two Souls will occasionally result in a warning. Instead of Levelling Up the base Soul, the attempted Fusion would create a new Rare Soul. Rare Souls' effects are entirely unique and can be completely game-changing when used in the right way. The Souls required to make each Rare Soul and the resulting Rare Souls' effects are listed below:
| Yo-kai 1 | Yo-kai 2 | Rare Soul Effect |
| Blazion | Flamurice | The holder's Attack gains Fire Attribute. |
| Appak | Chummer | The holder's Attack gains Water Attribute. |
| Pupsicle | Draaagin | The holder's Attack gains Ice Attribute. |
| Frazzel | Komiger | The holder's Attack gains Lightning Attribute. |
| Abodabat | Blandon | The holder's Attack gains Wind Attribute. |
| Mistank | Mr. Sandmeh | The holder's Attack gains Earth Attribute. |
| Swelterrier | Tunatic | The holder's Technique becomes Incinerate. |
| Faux Kappa | Drizzle | The holder's Technique becomes Waterfall. |
| Blizzaria | Alhail | The holder's Technique becomes Blizzard. |
| Tengu | Smogmella | The holder's Technique becomes Tornado. |
| Sir Berus | Eyesoar | The holder's Technique becomes Meteor. |
| Signiton | Statiking | The holder's Technique becomes Voltage. |
| Boyclops | Faysoff | Enemy Techniques have no Attribute. |
| Scarasol | Impass | The holder will only Guard. |
| Heheheel | Croonger | The holder takes less damage when Guarding. |
| Allnyta | Greesel | The holder's Inspirits never miss. |
| Pinkipoo | Cupistol | Increases chances of befriending enemy Yo-kai. Does not stack with Popularity. |
| Beetall | Rhinormous | Allies will not Loaf. |
| Snaggly | Whinona | The enemy's Yo-kai become more difficult to Purify. |
| Dazzabel | Leadoni | The holder gains a permanent Taunt, forcing all enemies to target it. |
| Ol' Fortune | Chilhuahua | The holder's attacks pierce resistances. |
| Dimmy | Blandon | The holder gains permanent Stealth, preventing enemies from targeting it. |
| Chymera | Nekidspeed | The holder gains a preemptive attack the first time they are in the front line. |
| Swelton | Mirapo | The player can spin their wheel for a longer time. Negates Spin-no-rama. |
| N'more | Furdinand | Enemy Restoration Techniques are weakened. |
| Pandanoko | Hurchin | Wisps appear more often. Does not work in multiplayer battles. |
| Robonyan | Hornaplenty | When rotating into the front line, the holder will guard. |