The Latics travel to Goodison Park on Saturday boosted by the return of the recently injured duo.
Defender Lopez suffered a hamstring tear during a game at Norwich in December.
Miyaichi has been on the sidelines since November, when the on-loan Arsenal winger sustained an ankle injury.
Both players featured in Wigan's U21s fixture against Nottingham Forest earlier this week and came through the match unscathed.
Martinez said: "Adrian Lopez played 90 minutes for the Under-21s and Ryo played 45 minutes, so I do consider them fully fit and I think they are available now.
"Emmerson Boyce and Antolin Alcaraz have come through our two previous games, against Reading and Liverpool, well enough.
"So I do expect everyone to be available for selection apart from Ben Watson, Albert Crusat and Ivan Ramis. Probably this is the strongest we have been this season."