I think the pool has a limited amount of creature choice, but an infinite amount of those specific creatures available. For me the issue is too much riding on RNG. The longer the matches go on, the shorter your list becomes to finish building up your creatures to 3 stars. To leave that solely to RNG is a problem because no matter which type of team you build, you're less and less likely to get what you need. It's pretty frustrating.

The arena isn't for me. I got one of the tigers, and that's enough. Maybe if they tweak it to be based more on decisions and less on RNG I may revisit it.

How can I merge/upgrade the companions? I have 2 of the same type and when I click one of them the other shows a star but when I click it it just swaps theyr spots.

@NightmareWolf2 It will automatically merge your companions. You need 3 of each star level for them to merge.

ex;

three 1 stars = one 2 star

three 2 stars = one 3 star

*Sometimes the Refresh isn't free after a Round ends, I am not sure what's causing this problem.

if you refresh the shop while the battle is visually in progress, the refresh isn't free but you get 2 paws as compensation