If you want to use a character's loadout so every other character can use it, score rank A or higher on all missions up to 5-5 with that character.

Character loadout	How to unlock
Albert Wesker's loadout	Get rank A or higher on all missions up to 5-5 with Wesker.
Barry Barton's loadout	Get rank A or higher on all missions up to 5-5 with Barry.
Chris Redfield's loadout	Get rank A or higher on all missions up to 5-5 with Chris.
Claire Redfield's loadout	Get rank A or higher on all missions up to 5-5 with Claire.
Extra loadout	Unlock all character loadout.
Hunk's loadout	Get rank A or higher on all missions up to 5-5 with Hunk.
Jack Krauser's loadout	Get rank A or higher on all missions up to 5-5 with Krauser.
Jill Valentine's loadout	Get rank A or higher on all missions up to 5-5 with Jill.
Rebecca Chambers's loadout	Get rank A or higher on all missions up to 5-5 with Rebecca.