You'll get another main phase right after combat, so unless there's something you really need to do before you attack, it's often beneficial to wait

Cerberus Sun-Blessed Healer Sun-Dappled Celebrant Sunderflock Sunscorch Regent Sunstar Lightsmith Superior Foes of Spider-Man Surging Sentinels Surrak Dragonclaw Surrak, Elusive Hunter Surrakar Spellblade Surris, Silk-Tech Vanguard Surtland Elementalist Surtr, Fiery Jtun Svella, Ice Shaper Svyelun of Sea and Sky Swarm Shambler Sweatworks Brawler Swift Spinner Symmetry Sage Syndic of Tithes Syndicate Enforcer Syr Carah, the Bold Sythis, Harvest's Hand Tackle Artist Taigam, Master Opportunist Talara's Battalion Talion, the Kindly Lord Tallowisp Talrand, Sky Summoner Tam, Observant Sequencer Tangle Golem Tangle Spider Tanufel Rimespeaker Tasigur, the Golden Fang Taster of Wares Tatsunari, Toad Rider Tattermunge Duo Taunting Arbormage Taurean Mauler Tawnos, the Toymaker Tazeem Roilmage Tazri, Beacon of Unity Tectonic Giant Teferi, Mage of Zhalfir Tellah, Great Sage Teller of Tales Tempest Angler Tempest Hart Tempest Owl Tenacious Tomeseeker Tenacious Underdog Tender Wildguide Tenth District Legionnaire Tenured Concocter Terra Stomper Territorial Allosaurus Teshar, Ancestor's Apostle Tester of the Tangential Tethmos High Priest

Its mono-white color identity means youre hurting for the best legends to include in the deck, and its ability requiring it to remove itself from the field is a bit counter-intuitive
The third mistake is ignoring the first two turns
This is enough to strike down almost every baby Basic Pokemon
Just because you pull a card directly from a pristine booster pack, handle it gently, sleeve and protect it right away, pack it very well and with extreme care