General Tactics
Magneto is strictly rushdown
Team positioning
Point
Magneto's best position by far. Using the switch glitch with his 1-frame 2LK can lead to instant, inescapable mixup at roundstart, and a good conversion assist like psylocke puts the threat of a fatal ROM or a snap behind every mixup. Although his Projectile assist is undeniably strong,
Mid
Not a bad choice depending on your team, since his EM Disruptor assist is great for zoners like Sentinel or Cable. Evaluate trade-offs carefully.
Anchor
At least Mags still has an assist to work with on mid, regulating him to an assist character is kind of a waste. Only do it if you really like his assist and you're confindent with him solo.