Didn't have time for decent reviews this time, but I'll share some quick thoughts.
Cosmic Sounds: Similar to your last entry. I feel the instruments are better sequenced this time. I think you could do more with Aquatic Base though, it is a great song with an amazing mood and some interesting chords that I believe you haven't used yet.
Tuberz: Nice tune, I like the part with Burst Man's main melody. Rocking! I feel the drums could be a bit more powerful and that the bass could be louder too. In general, the low end seems to lack some power. Also, not much Prison Lane this time (and you repeated the same exact riff from Round 1 )!
Mr. L - Once again, a pad! This is a very ambient track, sounds good. Main critique is that some leads feel very forced, which is why you put them in the background I guess. I'd really like to hear something in a different style from you, most of your tracks have a very similar vibe... The pads are awesome though, what do you use to build them?
ZeroTheMaster - Quite an unusual style for a Sonic/Mega Man mix! Main problem I have with this is that the instruments are too synthetic and don't really give a march feeling. Also, as therex said, the soundscape is a bit bare, there aren't many lows.
therex - This is unexpected . Percussions are fun as are the brass fills with the Toxic Caves bass. Bass is a bit drowned by the rest of the instruments and it makes the section beggining at 0:55 feel a bit "toneless". Flute section is a bit unfitting imo, too cutesy when compared when the rest of the song.
MindWanderer - Instruments are better this time! The horns are a bit low (and some notes may be off key) though. The arrangement is good, but it's usually a bit hard to mix this kind of songs in a slow orchestra style, not every melody fits that kind of arrangement. Arrangement feels a bit long too (and that flute note at 3:21 sounds terrible!).
Cash and Change - Drum sound could use a longer reverb, it sounds slightly strange now. The part where bass enters at 0:32 is quite cool. Marble melody sounds a bit waltz-y with the new rhytm . Section at 1:25 kills the mood a bit, the snare doesn't sound that good here. The higher pitched synths you used are nice. Song could use a pad, but it is cool anyway!