The downsides are firstly the life management, but Im sure a navigated player can leverage this resource as they need
Likewise, there are cards such as Carrot that On Play and On Attack ensure one of your opponent's Rested characters remains Rested for the foreseeable future
Luckily, your overall chances of getting a secret rare in a Mega Evolution pack are 19%, which is on the higher end of the regular Scarlet & Violet sets, where they ranged from 16% on the low end to 20% on the high end

Reward: Pack Hourglasses x12, Wonder Hourglasses x36, Shop Tickets x10 Secluded Springs secret missions Soaring Hoppip How to beat: Collect the regular art variants of Hoppip, Skiploom and Jumpluff ex Reward: Pack Hourglasses x12, Wonder Hourglasses x36, Shop Tickets x10 Legends Racing Across the Land How to beat: Collect the Two-Star full art variants of Entei ex, Raikou ex and Suicune ex Reward: Pack Hourglasses x12, Wonder Hourglasses x36, Shop Tickets x10 Secluded Springs Museum 1 How to beat: Collect the One-Star full art variants of Milotic, Stunfisk, Yamper, Latios, Phanpy and Azurill Reward: Pack Hourglasses x12, Wonder Hourglasses x36, Shop Tickets x10 Secluded Springs Museum 2 How to beat: Collect the Two-Star full art variants of Jumpluff ex, Entei ex, Raikou ex and Poliwrath ex Reward: Pack Hourglasses x12, Wonder Hourglasses x36, Shop Tickets x10 Pokemon That Can Use Attacks Immediately 2 How to beat: Collect the regular Mantyke, Igglybuff, Azurill, the One-Star Full Artwork Azurill, and the Crown Rarity Golden Mantyke

That means if you can turn even a single card to defense position and make its DEF 0, one attack from Chaos MAX dragon will result in 8000 damage, which is usually a win
I don't remember how many times we dueled already, but you're definitely my #1 opponent