Club president Enrique Cerezo insisted this week that Costa was a player Atletico needed to keep despite the arrival of Suarez from Barcelona.
And Simeone had no qualms with that as he spoke ahead of Wednesday's away match against Huesca.
"Costa and Suarez can start or they can play during the game, together and separately," Simeone said.
"Of course they can play together, but you have to see when and in what situation. The important thing is that both of them give us all the fire they have.
"Both Diego with his personality and Luis with his status in the game are very important players. We will see who starts on Wednesday.
Huesca vs. Atletico Madrid - Wednesday @ 1:00pm ET / 10:00am PT on beIN SPORTS
"When the president speaks, everyone is behind him. I agree with what the president said [about Costa].
"[Suarez has shown] absolute humility, despite the experience he brings. He wants to start showing how important he can be for the team on the pitch and in the day-to-day work for the group."
Asked if Suarez's Uruguay teammate Edinson Cavani would also be joining his attacking options, Simeone said: "I am not talking about the players we do not have on the squad and who cannot help us against Huesca, which is the important thing.
"Everyone knows Cavani, but we only care about the players who can lead us to the goals we set ourselves every year."
The emphatic start has seen Atletico heavily praised and billed as title contenders in the media, with Joao Felix also among their group of star-studded forwards.
"I do not stop for criticism or flattery," added Simeone. "They are part of the opinion that journalism needs to convey about what it sees and their work must be respected.
"We have to go game by game. Our opponents played very good games against Villarreal and Valencia so it will be a difficult game on a pitch where they need to be strong."