Whyte faces Helenius at Cardiff’s Principality Stadium for the WBC silver heavyweight belt on Saturday.
The 29-year-old will warm the crowd before Joshua looks to defend his WBA Super and IBF heavyweight world titles against mandatory challenger Pulev.
Promoter Eddie Hearn believes a victory for Whyte will put him in “prime position” for a bout at the world title.
But first the Brixton-born boxer must do the business against the Swede this weekend.
“I’m ready to rock,” Whyte told Sky Sports.
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“It’s a good fight. No-one can deny me a world title fight if I win this fight. No-one can say I’m not ready or I haven’t fought anyone.
“No-one can ever say that. I’m ranked highly across the board and I’m fighting a legitimate contender.
“I’ve seen him, he’s a good fighter, very well-rounded with a good jab and good boxing ability. You can see he’s got a very good amateur career.”
Wilder will defend his WBC belt against Bermane Stiverne in New York on November 4.
And if he is successful, then a huge clash with Whyte looks an almost certainty.
But first Whyte must focus on Helenius, and he hopes to put on a show in what will be a full house in the Welsh capital.
“I just want to entertain and give the fans good fights, because the fans are behind me constantly, supporting me, so I walk out there and do my thing,” added Whyte.
“I don’t walk out there to have wars, but if it comes down to it, I’ll have it.
“I hope he does stand and trade, because if he does I might trade with him, or use my boxing skills.