Inking and colours are really well done and some of those backgrounds are quite detailed. I quite like the way that you've captured the Marvel art style in your drawings, especially in the G2 portion. The definition in your inking style is impressive.
If I may offer some constructive criticism, you might like to consider more practice in drawing human faces. Also consider the way that you draw fingers. Your hands look fine when they're clenched as fists or holding guns, but I think there's room for improvement when they're opened. Keep in mind that fingers should not be of even length. One way to practice is to simply draw your own hands/fingers. If you're right handed and you want to practice drawing your right hand, I recommend placing a small mirror in front of you and drawing your left hand's reflection (naturally do the same for the left hand if you're left handed

). You can practice drawing your hand in various positions. But be aware that ladies' hands are typically more slender than a man's, so you might consider getting some images of women (e.g. fashion magazines etc.) and practising drawing those.
Also, G2 Megatron's head looks too big to me. It should be
smaller, but even the G2 comics didn't really do justice in emulating the toy's proportions. Beast Wars'
Megastorm was often drawn with more toy-accurate proportions.
