Quoted By:
Metal Gear Solid.
It would be the same MGS thing, solo sneaking mission, big urban base, and procure-on-site, but it's also an RPG where you fight in Chrono Trigger-style battles with pokemon alongside you. You can use weapons like normal in MGS outside of these battles, but if multiple enemies get in too close to you, the battle type where you use your pokemon is activated. The Pokemon you acquire through various methods, depending on their type, have special overworld abilities a la Pokemon Ranger that you can use to access shortcuts, secret areas, and exploit boss weaknesses with.
Bosses are also fought as per normal MGS style, but each boss owns a legendary that your entire party fights in a seperate, yet simultaneous battle (ie. You might fight Rex while your pokemon repel a Rayquaza from also fighting you in the Chrono-trigger style battle. You can fight either battle at any point in the entire fight, but while you're fighting one fight, the other one is paused until you resume it, which pauses the OTHER battle if you're not finished with it)
Pokemon: Steel Cog Frozen Edition