General Tactics
Since close-range is where Mag's potential truly shines, most of his gameplan revolves around getting in as fast as possible and not letting go til the opponent's team is toast.
Roundstart
Run Magneto as an assist and switch glitch him in (hold A1/A2 during versus screen) while holding cr.LK makes his 1-frame low come out the second the game starts, forcing the opponent to eat an immediate mixup. This can be beaten with proper timing from the opponent, but this just opens up more layers which is exactly what Magneto wants.
Neutral
If you're having issues getting in, SJ jHP> adc jHP backwards or forwards serves as a near-impenetrable retreat or rushdown tactic, although you want to stick to the ground since that's where his tools are the strongest. Use your air dash/wavedash to dodge assists or your own assist to counter-call the opponent's defensive attempts. Hyper-grav is a good fallout if the opponent keeps trying to fall on you from the air, and on hit puts them completely at your mercy.
Pressure
When you’re close, 2LK>MK> A1/2 either gives you plus frames or a free confirm. Magneto’s tri-jump (sju > ADC df) allows him to force the opponent to guess between a nearly invisible high/low/crossup. If your mix is blocked, use an assist to keep yourself safe and reassert your pressure again; but be on the lookout for reversal assists and push block, if you’re predictable and don’t take your opponent’s habits into account you could eat a nasty counter hit. It’s usually best to take your pressure slow and establish layers—-playing Magneto haphazardly is basically giving the other player a free win and nobody wants that! Once you've opened the opponent up, you can ROM them to death, snap in their assist, or just reset them whenever you want---be warned, it's easier said then done.
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
Usually the only time you'll see Magneto mid is in order to absue the switch gltich, but its not a bad idea to keep him here either. His projectile assist covers the entire ground, forcing opponents to take to the skies or get pushed back to the other side of the screen. Not a bad choice depending on your team or the matchup, but evaluate trade-offs carefully.
Anchor
Regulating Magneto solely 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.
Picking Teammates
Magneto isn't super picky about his teammates so long as he's point, but he does get a lot out of the right assist choice. MSP (Magneto A/Storm A/Psylocke A) is one of the strongest shells in the game, giving Mags both a neutral and defensive assist, letting convert off of any stray hit into ROM and allowing him escape the screen for two bars with a Hail Storm DHC. His EM Disruptor assist is great for zoners like Sentinel or Cable, and he can still abuse his strong points with one assist
Tips & Tricks
Text
Fighting Magneto
Text