He has the new Backup mechanic, which means he puts a +1/+1 counter on a creature when he enters the battlefield and grants that creature the rest of his abilities
While not mentioned in the FAQ, another reason is that placing tabs will add extra thickness to the surface, and if you had tabs attached to roughly the same spot on all sleeves, that thickness will add up to form reliefs and damage the cards if the band you use to hold the cards was too tight
You can only use this effect of "Heraldic Beast Aberconway" once per turn
But he just reappears in Season 4 alive but still with his fatal heart condition, with no explanation given as to how he's alive even though we clearly saw him die in the previous season
Owner's Pokmon are Pokmon cards which reference the specific trainer they belong to - generally a well known character from the anime and/or games
Of course, the gorgeous Battle Menu Magic card art brings even more Final Fantasy magic to the table than just a reference to its menu