Dude, your DK is good. You know that mansion like the back of your hand, bair mindgames to reverse giant punches, overall the bair game was nice.
To help you, it seems like you don't know what to do when you're being pressured. Keep moving away from the person attacking you if you're in the air, especially MK. When Hylian is waiting on your attack with his shield, side b it, it will probably break. When G&W is uair'ing you, don't air dodge. That's what they want you to do, try fastfalling torwards him instead, maybe even dair might work if he keeps doing it. You might want to try moving down and away and bair him.
Hylian was trying to pressure you a lot with bair, get a punch charged when he's not there and paaunch his approaches. Use up b to approach as well, the bairs are sort of predictable and up b's super armor does wonders, it makes a great anti-approach too. You'll be living much longer than all the light characters you play so trade hits because yours matter much more. When Hylian grabs the edge to stay away from your new invincible stock, run off and bair him because I don't think he'd want to challenge someone who was invincible.
Hope that helped, also you're responsible for finding someway to mess with people who hold up. Somehow.
Edit: Take Ike to Japes, not Mansion. Ike is so bad on Japes and DK is sooo good. Also, DK's ftilt is good for stopping approaches, it has good range and priority too, you didn't seem to use it.