mewtwo armored

Mewtwo (Armored) => is Pokemon dex #150 (Legendary Pokemon)

Opendex
=> Pokemon that you already have / have registered in your Pokedex, shown as an image with Pokemon details

Non Opendex
=> Pokemon that you do not yet have / have not registered in your Pokedex, shown as a black silhouette (meaning you have seen it in a raid/gym) or just the Pokedex number

Opendex Trade Requirements
1. Must have 100 Stardust
2. Must have it as Opendex in your Pokedex

Non Opendex Trade Requirements
1. Must have 20,000 Stardust
2. Still a silhouette or you don't have the Pokemon yet

Note => Non Opendex Tip (Legendary Pokemon / Shiny Pokemon) willing to be friends until Ultra Friend to reduce stardust cost (80,000 stardust). If willing, buy the cheapest Opendex Pokemon you like at Wantau Store, then chat the seller to request a 30-day friendship (Ultra Friend).

How to trade Opendex or Non Opendex can check the link below: