Go with it if you want that old 2000s forum vibes in your card
He'd be better in a deck that focuses on both paradox triggers and copying spells, however, making him a less effective combination than Yasmin and 13
With the Slowpokes and Drowzee being weak to psychic they take double damage if they lose the coin flip resulting in KO'ing the base set Slowpoke and taking Drowzee and fossil Slowpoke to 10 HP
When it ETBs, you're going to get one creature out of eight cards (four of yours and four of your opponent), and because of your deck restriction it's pretty positive that you'll get a free creature out of the deal
Once Vaultborn Tyrant's second ability has triggered, lowering the power of the creature or removing it from the battlefield won't stop you from gaining life and drawing a card
If the title mentions Holo or Reverse Holo, that's what you'll receive