Descent is a classic.
Cybernators has slightly different controls than Metal Warriors. Cybernators lets you hold your direction of your mech & gun with one of the shoulder buttons, whereas Metal Warriors has shoulder mounted weapons you can pick up that use that button.
Metal Warriors is by far the most entertaining multiplayer SNES game I've ever played. I've played it for like 6 hours straight with a group of 5 people. There's 6 mechs from which to choose in it: Nitro, Havoc, Prometheus, Drache, Ballistic, & Spider. Every mech has 3 weapons/abilities.
Nitro gets a gun, a beam saber, & an energy shield you can leave in place & run behind, or deploy when running away to avoid getting hit in the back. Nitro can also infinitely use the jets on his back.
Havoc has a chain gun, a chain for melee, & a squat dash similar to Trigger. He, however, is limited by his feet jets on jump height.
Prometheus has mines that float up, a gun that explodes & sends shrapnel in 8 directions, & the deadliest flamethrower ever. He can't jump at all, but can build bridges.
Drache's face buttons are for firing in all 8 directions without any time wasted to re-aim a weapon. His dive bomb can kill the opponent in about 2 to 3 seconds. Drache is full flight & doesn't land.
Ballistic can slam while a ball, & has 2 guns while gun platform, a normal one & one that charges. The lower charge is a barrage of maybe like 5 or so powerful shots, & the charge is one even more powerful shot that knocks them back & deals damage based on time they spend inside it. Ballistic just jumps like normal, but the slam is 8 directional, so you can bounce up elevator shafts & stuff.
Spider walks on walls. His shield is a cloak rather than a shield. He has a normal gun, a web that can trap opponents in place, & a face strike.
Just keep picking Scramble after matches & it'll give a random stage & random mechs to both players. It's so fun.