I would honestly like to see an upgrade to existing pets. Basically these premium pets are different skins for the pets we normally get from the eggs, right? So abilities are the same, stats are the same and you aren't gaining any advantage to the premium pets besides look. Why not allow us to buy the skins like we do for characters? I think this would justify paying 250 or even 400 gems as you know what you are going to get and the rarity of the pet is chosen by the player.
While I really like the idea of events I would like to see them not as chance but by putting in the work. Unless you add that after X amount of runs there is a guaranteed drop, many people won't get anything during the events. Which is just going to hurt the overall game experience.