The Pikachu Illustrator card dates from a reader competition run in Japanese magazine CoroCoro Comic from 1997 to 1998
Allowing artifacts to be returned from your graveyard following the demise of any of your opponents' creatures, Glissa can even then bring artifacts to your hand from the graveyard using her activated ability Additionally, Glissa comes packing two relevant combat keywords first strike and deathtouch
A new take on a classic creature, this iteration of Niv-Mizzet fuels your hand as long as you're dealing noncombat damage to your opponent
Thrasios is mainly for cEDH (Competitive EDH), so you'll be putting a big unnecessary target on your back using him without an infinite mana strategy
Pick that goal first, and the best Pokmon booster box to buy basically reveals itself
On top of that, though, Harbinger synergizes well with the other Merfolk in the archetype