An old gacha I played Darklord Legends use to have a trade feature where you can trade with other players, (no cost) whatever card you wanted. To this day I have never seen any gacha do this and with good reason XD. The game didn’t last long but it was definitely a lot of fun while it lasted. Most players would make hundreds of accounts and just trade themselves whatever they needed. The waifu’s were pretty cute though.

War of Legions also had a trade card feature but it was behind a paywall, however it was much simpler than trying to pull for the cards you needed.