[quote=@Stern Algorithm]
[@Lugubrious]

Can Din buff Gogoat with the Spell of Spring? What would such a buff entail? Also, do I play Gogoat like a separate character with its own XP bar and such? Do you have 4 pokemon attacks that you wish to assign, or should I pick?
[/quote]

Spell of Spring, judging by its description, has no buffing properties, so no. Gogoat can be treated like an NPC, and kept track of via its pokeball in your sheet's equipment section, without EXP. You can pick your pokemon's attacks.