I've never said Sonic's attack will not be effective at all, I was comparing their defensive abilities. Zero has higher defense than Sonic, that's what I was trying to say.

Can Zero chase after Sonic successfully? No. I admit that Sonic is fast, but Zero and Sonic are not racing here. So what if Sonic is fast, Zero can just wait for Sonic to attack and then counter him. In a situation where their attacks both hit, Sonic will get more damage. Why? Aside from Zero having higher defense...try to imagine running into a saber with full speed.

Zero doesn't have to chase after Sonic and attacks, he can just put his saber to the direction where Sonic is from, and react quickly so that Sonic runs into the saber. Zero might walk/run slow comparing to Sonic, but he can jump pretty far. With a simple dash-jump, Zero can travel almost a full screen. (And that's no charging required.) Therefore, if Sonic ever stops while he's close to Zero, Zero CAN catch up and attack from then on.

Zero can also dodge attack in mid-air by a second Jump or Air-Dash, also, he can hold up to any wall. Then he can either kick jump to the top, or slide - neither of those move will stop him from attacking/defending though, Since he can pull out his saber while he's at the wall.

Why can't Zero react to the speed? Because of his carcass? But Zero CAN react against teleporting enemies...I think that reacting to teleportation would actually require more...reflexes...

Zero's shadow is different from Zero's clone. His shadow is an attack which is performed when Zero finished his dash, he sent in a shadow in a split second and slice through anything that's infront. While it might not hit Sonic, it will certainly slow him down, make him change direction and thus making his next move more predictable for Zero.

Zero's Clone, on the other hand, is a clone which can attack just like Zero. It will make the battle to be a 2 vs 1 for awhile, in fact. Also, the clone is identical to Zero, so it is not possible to tell one of them from another.

Zero also has two E-Tanks (Some version he has 3...but meh)...which some might think those are items, but no. E-tanks (E-Can, literally) were once items in Megaman series. (In the manga, you can see Megaman takes out a can and drink...) E-Tanks in MMX series, however, are built-in device in the Maverick Hunter's armor. Where is my proof for that? X's amount of E-Tanks depends on which armor he chooses to wear, therefore the E-tanks are built-in.

Therefore, 2 E-Tanks and 1 W-Tanks. W-Tank would enable him to do several more Gaia Attacks, (Invincible when it is executed) and E-Tanks fill his energy to full once again. But he might not even need to use them... It depends on how much hits Sonic can stand against.