While I agree with the fact it's a rather easy MU... have you guys actually played Bowser players? No offense, but it doesn't seem like you guys know much about Bowser except for Fortress OoS.
Interesting things to know:
-SideB cancels landing lag.
-Grab release shenanigans. Lots and lots of them. CGs on many characters. Guaranteed followups on most of the others.
-Lots of range.
-Great at punishing spot dodges.
-His jab is really good.
-If he SideBs while falling towards a platform, if he falls through it the move stops and he goes into a neutral aerial state, meaning he can instantly perform any aerial. For this reason, platform stages are quite good for him.
-Utilt is a good Anti-air move and KO move, but leaves him very open.
-UpB has startup invul both on the ground and in the air (to my knowledge), meaning he can use it to avoid gimps and break out of combos. However, it leaves him very open in the air, can be SDI'd>punished, and is slower to come out then on the ground (I believe), which, coupled with the fact it makes him rise, makes it less than ideal for combo breaking, but it's pretty much his best/only option.
-His aerials all kind of suck except his Fair, which is pretty good. His Uair is good for punishing predicted air dodges too.
-He kills early.
-Gets comboed to hell, as many already said.
-Can be inhale>footstooled (Can avoid it by immediately UpBing, but that pretty much kills him.)
-Firebreath is a pretty good spacer/edgeguard when used sparingly, but it's effect is lessened against Kirby since we can go around it with our many jumps, and we can SDI>Uair it.
That's about all I can think of atm.