I learned a few things so I'd figure I would upload a vid.
Metal Slug XX is a remaster of metal slug 7 (no relation to MSX/Metal slug 2 remaster metal slug X). A very fun game and it adds the military from king of fighters: Ralf (rapid punch and 2 hits to die), Leona (earring bombs and more ammo, free here from ms7 dlc) and then Clark who just throws an enemy who lands on his feet in a super argentine backbreaker. No idea why the control for that is so unintuitive, special L1, fire square and up. There are apparently invincible frames for it, and his last name is Still 🤣.
Challenge mode (combat school if you wanna do a level with infinite weapons instead of lives) is a nice revisit (and better than the takeover's repetitive survival mode with a dogfight that only first missiles, nice try for a beat 'em up though that has challenges too).