I made a tier list of every single pre-battle taunt message.

Let's Smash Bro Tier
Let's smash, bro!

The Only Good Response Tier
Talk is cheap!

Respect Tier
Good luck! Have fun!
Here's to a good fight!

Humble Tier
Go easy on me!
You look tough.
I'm looking for a challenge.

Meme Tier
YOOOOOO!
Settle it in SMASH!
I'll grab ya... and I'll throw ya!
Eat this! MEGASMASH!
High energy! Move that body!
I hope you like to be countered.

Only If You're Playing The Right Character Tier
It's time!
I'm fully charged!
Gotta go fast!
Lightning speed!
Close range only!
Let's-a go!
I challenge my fate!
Time to tip the scales!
Keep your eyes open!
Trust your instincts!
Looks like we don't have a choice.
I can change the future!

Big Talk Tier
I won't lose!
I play for keeps...
Here I am!
Bring the pain!
I'll take you down!
Make no mistake - I will win!
Get ready...
Get ready!
Fight me!

Anime Tier
I won't hold back!
It's all or nothing!
Time to go all out!
You can't stop me!
I'll give it my all!
I'm itching to fight!
I'm burning to fight!

I Lost Last Game Tier
I'll win this time!
I can keep going!
I've got you now!

Meh Tier
It's go time!
Time to fight!
Hey!
My mind is clear!
Come on - let's go!
Here I gooooo!
Now you see me!
Here I go!
I'll face you...
I'm excited!
Ready to fight!
I'm pushing through!
I'm going in!
Let's get started!
Go go go!

Mad Tier
Now I'm mad!