Shadow Alakazam

Shadow Alakazam sits on a very interesting and unstable throne. It technically has the highest Psychic Type DPS in the game with its legacy Psychic moveset generally speaking, surpassing even Deoxys-A and Psystrike Mewtwo, but its advantage over the later is so miniscule that it's not really worth raising unless you're desperate for a Psychic attacker due to just how much lower its TDO is. To say the least, it's a significant drop.

...and while Shadow Alakazam may look cool standing atop a gym, it's an atrocious defender due to how frail it is.

Best PvE Offensive Moveset

• Confusion and Psychic* make for top-tier Psychic DPS
• Future Sight can replace the legacy Psychic* in that role, but it does weaken Alakazam's performance. 
• Psycho Cut provides better energy gains and dodging and may be situationally superior, but it's generally behind Confusion in terms of DPS
• Counter* goes with Focus Blast to make Alakazam a high-DPS pseudo-Fighting Type attacker, but it's really too frail to reliably throw out a charged move, and isn't exceptional in the role.
• Shadow Ball can pump out some Ghost Type DPS, but it's not fantastic.
• Dazzling Gleam* is a decent move, but it's lackluster on Shadow Alakazam
• Fire Punch is basically worthless here.

Best PvE Defensive Moveset

• Confusion is the top choice for defense, as it's one of the best defensive moves period.
• Counter* can provide some decent counter-coverage, as the name suggests.
• Dazzling Gleam* or Shadow Ball both work, though Fire Punch's bring 3-bar means it's generally best
• Psychic* is another decent choice, but mono-typing is not great on defense.
• Future Sight and Focus Blast will probably never get to be used, and Psycho Cut is just plainly inferior.

Counter is generally preferred for its superior damage output and wide relevant coverage, despite STAB and superior energy generation with Psycho Cut. 

Fire Punch costs the least amount of energy, and can be used frequently. Psychic is a move that hits hard with STAB, but is limited by availability. Shadow Ball provides coverage against Alakazam's weakness to Ghost-types, in addition to relatively neutral coverage overall, but lacks STAB. The rest of Alakazam's charge moves cost too much energy to be viable; Alakazam will very likely faint by then.