Level-Up cards must be played onto the corresponding Pokmon like evolution cards (though, in one rule change, it must be the active Pokmon), allowing for a variant of the Pokmon with greater HP, damage and additional attacks - as well as being able to use the moves of the card from which they levelled-up, unlike evolutions
Plenty of cards from that set offer benefits based on the number of party members or even having a full party with one of each creature type
The rest of the deck goes along with the Kindred Pirate theme of getting all sorts of Pirates in play and attacking until your opponents die
Burn is still not the best strategy in EDH, but I love that we have new toys to play with
Imagine Hydroid Krasis, but instead of lifegain, you get vigilance, flash, and an extra +1/+1 counter and card draw whenever opponents search their library
I can see Inspirit, Flagship Vessel becoming a key part of my Commander Deck rotation