BOMBERMAN ActZero

Easiest method:

Do NOT do this in First Person (actually third person but whatever) mode. You'll NEVER make it in time; both because some enemies take forever to kill, and the difficulty spikes like a monster. Do it in Standard mode, since all enemies die in one hit, unless they pick up a life block, in which case they can take an extra 2 hits it seems, if they are blocking the blast.

The first 10 waves or so are the toughest, since you can also die in a single hit, but once you build up life blocks, it becomes hysterically easy. Combine that with the Penetrating Block (I didn't find Remote Control to be that useful), max Fire Up, Speed Up, and Bomb Infinity (With Bomb Through for good measure), and you can decimate your opponents in as little as 10 seconds.

(Block through isn't really nessissary if you have Penetrator, but it can still speed things up)

Additionally, each incriment of 20 levels (LV 20, 40, 60, and 80) has a shit-ton of life blocks. Once you get to 20 lives or so (there doesn't seem to be a limit, but the highest I got was 40-something), you're virtually unstoppable. Plus, if you take a hit, you only lose one life block, maybe two depending on the duration of the blast.

I did this in about 58 minutes. That has to be some kind of record.