Minecraft wiki entry for ride, associated text: ride <riders: target> start_riding <ride: target> [teleportRules: TeleportRules] [howToFill: FillType]
Makes <riders: target> ride on <ride: target>.
ride <riders: target> stop_riding
Makes <riders: target> dismount.
ride <rides: target> evict_riders
Makes entities that are riding on <rides: target> dismount.
ride <rides: target> summon_rider <entityType: EntityType> [spawnEvent: string] [nameTag: string]
Summon an entity at the position of each of <rides: target> that are rideable and not full, then make them ride on <rides: target>.
ride <riders: target> summon_ride <entityType: EntityType> [rideRules: RideRules] [spawnEvent: string] [nameTag: string]
Summon an entity at the position of each of <riders: target>, then make <riders: target> ride on them.