So it has been... well a long time since I've done any Shadowrun but I'm toying with the idea of starting up a campaign to play on alternating weeks with my group to mix up the Labyrinth Lord campaign we've been running for the past year or so.

The big reason Shadowrun kinda got pushed to the side though is because one of my players is... well he's a power gamer in the purest sense. It's a big part of the reason we play LL actually... It's pretty tough to powergame when chargen consists of "Roll 3d6, six times in order and pick a class from the six available". He's a great guy, and a lot of fun to play with, but he can be challenging to DM, since I don't have the time or inclination to continually try to 'outplay' his character builds. I like the idea of giving him the opportunity to stretch a bit though, since I can tell he feels a bit constrained by the D&D game at times.

At any rate, the first limiting factor will be that it is the core book only. This is easy, since I only own the core rulebook. I've got a ton of splatbooks from earlier editions, but they'll just stay off the table except for fluff purposes. Also, from my limited experience with 5th ed it feels as though it is a lot tougher to game the system with the introduction of limits it might help prevent him pulling out a summoner who rolls 25+ dice and summons bloodzilla for breakfast. That said though, I'm sure there are still other ways for him to break the system in creative and interesting ways, so my question is, are there any red flags to look out for?

In a purely opportunity cost way, SR5 is pretty balanced. The key thing to keep in mind is that characters will tend to look more powerful than their SR4 counterparts, but they are actually less powerful relative to the rest of the game world. Also, characters have to deal with a lot of limiters such as background count, the choice between running wireless (and risking getting bricked) or turning wireless off (and losing some dice); overwatch score, and, of course, limits. Furthermore, SR5 takes the nerf bat to most dice pool modifiers, making them either more expensive or less effective. Some things got nerfed less than others, though...

Trolls:
Yeah, they got hit hard in a lot of ways, but they are still the go-to for tank or melee builds.

Mystic adepts:
They look daunting, but they basically need to front-load at character creation, and their growth slows after that.

Adepts:
Only powerful because augmented characters were nerfed harder. But they can get extra powers from mentor spirit bonuses or qi foci, and as in SR4, they can get a mix of augmentations and magic to have the best of both worlds - although the Priority character creation system makes that approach more costly.

Spirits:
The only really potentially unbalancing thing I could see. Spirits are (at high Force) powerful and difficult to damage, especially for mundanes. Drain should help keep things from getting too far out of hand, but even Force 5 or 6 spirits can be tough.