This is a list of recommended characters for scouting in G Generation Eternal. It also covers how to scout in G Generation Eternal and the unlock conditions. Please use this for your scouting needs.
Recommended Scout Characters
The recommended scout characters in G Generation Eternal are "characters that can meet series restrictions" and "characters that match the unit's type and performance". Compared to characters obtainable from Gacha, their performance is inferior, so scout them to fill any missing slots in your team.
Characters that can meet series restrictions

In Main Stages and Eternal Road, there are series restrictions for team formation. You will only be able to deploy characters from specific series, so use scouting when you are short on characters.
Characters that match the unit's type and performance

It is also recommended to scout characters that match the unit's type. By matching the types of the unit and character, you can maximize the ability effects, so basically, you need to form your team by matching types.
Assign to units that match the character's stats

Character stats vary. In the example image above, Garma Zabi performs better when assigned to a unit with many ranged weapons, while Ortega performs better when assigned to a unit with many melee weapons.
Unlock Conditions for Scout Characters
Unlocked by progressing through Main Stages

Scout characters in G Generation Eternal are unlocked by progressing through the Main Stages. You can check which characters have become available for scouting on the rewards screen after clearing a specific Main Stage for the first time.
Unlock conditions are displayed for unobtained characters

By selecting an unobtained character on the scout screen, you can check the unlock conditions. You can only check the unlock conditions for characters you don't own; once obtained, the unlock conditions will no longer be displayed.
Gacha-exclusive characters cannot be scouted

Characters obtained when acquiring units from Gacha cannot be obtained through scouting. There is no other way to get them other than being pulled along with units from Gacha, so save up your Diamonds and Tickets and pull on the Gacha.
How to Scout
Can be done from Characters in the Enhance menu

To scout in G Generation Eternal, go to 'Enhance' from the menu at the bottom of the screen, then tap on Characters to go to the scout screen.
Unlocked by clearing Mobile Suit Gundam Stage 3
The scout function is unlocked by clearing 'Mobile Suit Gundam Stage 3' in the Main Stages.
Capital is required for scouting

Capital (money) is required to scout characters. The amount of Capital needed varies depending on the character's rarity: SR costs 3000, and R costs 1000.