It pairs beautifully with Baxcaliburif it's on the field, you can start slapping those Energies onto your Pokemon like theres no tomorrow
In addition, while Haakon cant be played from the command zone, he can be played from your graveyard, which works even better since it avoids the commander tax issue
If the land entering the battlefield causes any triggered abilities to trigger, those abilities and Rocco's ability will be put on the stack at the same time, with the abilities controlled by the player whose turn it is going on the stack first (and thus resolving last)
Its a surprisingly versatile card that interacts with the Lost Zone beautifully and has a powerful Knock Out VSTAR Power with Star Requiem
I think it will be good for the format due to fast mana such as Simian Spirit Guide, Tron Lands and Bouncelands being viable in the format
Storm, control, and Splinter Twin decks all benefited from streamlining their draws and casting cheap spells