As you may have read in the title, I have a few suggestions for pokemon that could be added to Skyblock. I used each pokemon's description and story to make these decisions, so you know where I'm coming from with this.
EDIT: ADDED GULPIN/SWALOT
|Zigzagoon| Inventory transfer from pokemon to a nearby chest (5x5 for pokemon, 3x3 for chests)
|Linoone| Increases range by 1-2 blocks
[100,000 buy, 250,000 upgrade]
|Ralts| Regenerates all players' health at a rate the same as regeneration 1, with half the range of a beacon
|Kirlia| Increases regeneration range to the same as a beacon
|Gardevoir| Removes fall damage for members of an island, Increases regeneration rate to regeneration 2
[200,000 buy, 500,000 to Kirlia, 1,000,000 to Gardevoir]
|Cacnea| Automatically produces cactus in its inventory, at a rate of 5-10 every minute
|Cacturne| Produces cactus at an increased rate
[50,000 buy, 250,000 upgrade]
|Roselia| Automatically generates flowers at a slow rate based on the island biome
|Roserade| Increases flower generation rate
(Flowers are used for dyes for wool and banners for shields)
[100,000 buy, 250,000 upgrade]
|Beldum| Tells you how long it will take to fill containers in a 5x5 area
|Metang| Also now tells price of items in containers
|Metagross| Automatically sells items in containers in a 7x7 area {Money goes to owner}
[50,000 buy, 250,000 to Metang, 500,000 to Metagross]
|Attack forme| Increases pokemon loot gain by 1.5x
|Defense Forme| Players take 0.5x damage from mobs and potions
|Speed Forme| Increases pokemon speed by 1.5-2x
Buy on website - Devs decide price
|Gulpin| Gives you a chests's worth of space to delete items. Also picks up items from the ground and adds it to its inventory.
|Swalot| Increases space to a double chest, adds option to store items.
[25,000 buy, 50,000 upgrade]
Descriptions of these pokemon found on the Pokemon Bulbapedia, not sure if safe to post link so I won't