Here’s a collage of the various Espers in the game. Most are from G1 but others are not, like Sunshimmer being G3 but included to connect to Sunset Shimmer. There are a few little nods to G1 story as well, what little I know of it. For instance, Majesty had magic horseshoes that can turn her invisible, thus she replaces Phantom who casts Vanish on the party.
Some details on certain ponies:
Majesty was chosen for Phantom because she has magic horseshoes that can make her invisible
Gusty was chosen for Kirin due to matching its color palette
Starswirl and Powder had specific limitations on their pose, since they had to match up with the existing attack animations
It can’t be seen here, but Firefly is animated in-game
The 6 ponies for Legacy were the first 6 MLP toys released
Most characters are trying, as best as pony anatomy allows, to match the pose of the original esper.
Majesty was chosen for Phantom because she has magic horseshoes that can make her invisible
Gusty was chosen for Kirin due to matching its color palette
Starswirl and Powder had specific limitations on their pose, since they had to match up with the existing attack animations
It can’t be seen here, but Firefly is animated in-game
The 6 ponies for Legacy were the first 6 MLP toys released
Most characters are trying, as best as pony anatomy allows, to match the pose of the original esper.
No, the hack is based on the Super NES version with no GBA Espers.
Edited