For those who want all the various powerup medals (the ones with numbers) you won't get those just playing through and beating the game normally. Well, you'll probably get like one or two of them that way.
What I find works is start a new game, kill every enemy, and proceed until the first boss. Intentionally lose at the boss, go back to main menu, continue your game, except at the level select go back to level 1 and repeat doing this sequence.
About every time you do that you'll earn either 1 or sometimes 2 of those numbered powerup medals as well as the powerups. If for some reason you don't earn one, you'll definitely earn 1 the next time.
I think it may have something to do with those +1 items the enemies sometimes drop?? But I'm not sure. All I know is do the above and you'll get all the numbered powerup medals, which annoyingly you won't get if you just played through and beat the game like a normal person.
Aside from that bit of grindy annoyance, the game has quite a bit of lag to it in places and isn't always the most responsive. Hope it helps anyone trying to finish out those medals.