Are there any multiple characters platformer that sounds like this ?

Worms, by Team 17, with unlimited character changes. It's still turn based, but it does not change much for the purpose of this discussion.
To be honest, I think allowing unlimited, instant character switch would result in consistent ease of the puzzle elements. I guess that would be what you're looking for!

Not that I know of, but your idea seems interesting and commandos is a great game to get inspiration from

Commandos, by Pyro studios does not have explicit planning phases but the phases naturally emerge. The game is mostly slow-paced, sequences requiring careful timing and fast-paced actions (as far as I remember) can be easily interrupted as most levels offer plenty of safe zones.
It's also worth noticing most levels I recall started from a safe state. This effectively allowed an initial "plan" sequence which is ideally as above described, albeit implicit.
It allows unlimited character switch and still retains a strong strategic/tactical element. Completing even the simplest missions could easily take 10+ minutes.

Slick,
I'm afraid you might be misunderstanding the meaning of the terms I'm using in my previous post.

Are there any multiple characters platformer that sounds like this ?

Worms, by Team 17, with unlimited character changes. It's still turn based, but it does not change much for the purpose of this discussion.
To be honest, I think allowing unlimited, instant character switch would result in consistent ease of the puzzle elements. I guess that would be what you're looking for!

Not that I know of, but your idea seems interesting and commandos is a great game to get inspiration from

Commandos, by Pyro studios does not have explicit planning phases but the phases naturally emerge. The game is mostly slow-paced, sequences requiring careful timing and fast-paced actions (as far as I remember) can be easily interrupted as most levels offer plenty of safe zones.
It's also worth noticing most levels I recall started from a safe state. This effectively allowed an initial "plan" sequence which is ideally as above described, albeit implicit.
It allows unlimited character switch and still retains a strong strategic/tactical element.