Action games for Nintendo DS? [GA]

I remember playing Call of Duty 4 on the DS with a friend that owned it and if one person has it, you can get other people to play regardless if they had it and it was fun, always wanted it but never did!

Solatorobo might be o-k. Maybe if they like actions in the action RPG games, even though it's probably action/adventure.

Do you mean shooter like fps shooters? Are there even that many on the DS..

Contra 4 is essential if he doesn't have it yet.

From the top of my head (and excluding the ones already mentioned), Mega Man ZX and Metroid Prime Hunters

Castlevania: Portrait of Ruin
Castlevania: Order of Ecclesia
Mega Man ZX
Mega Man ZX Advent
Kirby: Squeak Squad
Kirby Superstar Ultra
Kirby: Mass Attack
Star Fox Command
Super Mario 64 DS
Wario: Master of Disguise

Not action, but a great puzzle game that can get frantic: Meteos

Since it's a normal DS, it can also play GBA titles. Some great GBA titles I'd suggest are:
Gunstar Super Heroes
Sigma Star Saga
Astro Boy: Omega Factor
Blackthorne
Castlevania: Circle of the Moon
Mega Man Zero 1-4 (A collection is available for DS as well, all 4 games in 1)
Mega Man and Bass
Wario Land 4

Ninja Gaiden: Dragon Sword , if he can use both hands well enough. It's a different take on the franchise, but fun can be had.
Castlevania titles of course.
Assassin's Creed II: Discovery , a side-scrolling entry into the franchise that made the series closer to it's Prince of Persia roots.
Metal Slug 7. While not as great as those that came before it in the franchise, it's still good fun.
Okamiden , a smal Legend of Zelda like experience.
Dragon Quest Heroes Rocket Slime. Play a slime in simple combat, but also pilot a giant mech and throw objects at the enemy (be it cannons or random rubbish or your friends or even enemies that invade your mech).
Aliens: Infestation if he is up for a horror themed survival game from WayForward. Side scroller with a lot of depth of trying to ensure everyone survives against the Xenomorphs. Still my favourite game in the franchise.

DS has some Resident Evil games too or older Smash Bros,

Thanks for the recommendations guys.

(Also, make sure that GA doesn't go to waste.)

The DS Contra.

What about Advance Wars: Dual Strike?

Its more of a turnbased strategy game, but supposed to be really good.

The Lego DS games are always fun.

Not really action game but the RE 1 port on DS; Deadly Silence is pretty good.

Anything made by Nintendo is always great.

Tbh for action-games PSP's games are better than DS
But if you want
Kingdom Hearts 358/2 Days
The world ends with you
Also, metal slug, Castlevania, Final Fantasy DS games? (Not sure if these are action games though)
Hope it helped you xD