Here is how Ryan and the gang arrive in Danny Phantom's world in Crash, Thomas and Ryan meet Danny Phantom.
(we see Ryan Tokisaki with Optimus)
Ryan Tokisaki: So. Prime. You think that Megatron is good? I did mention him back in the Date A Live world.
Optimus Prime: Of course. He has been since we saved him from Unicron.
Ryan Tokisaki: I guess he lost his interest in inflicting oppresion. Same thing for Evil Ryan in the Rainbow Rocks film.
Optimus Prime: Indeed.
Sci-Ryan: Come on. Come on. How hard is this crossword to crack?
Ryan Tokisaki: I just heard that Knock Out's on his way back with a new adventure.
Matau T. Monkey: Yeah.
[Knock Out drives in and transforms just in time to catch a syringe Ratchet drops]
Ryan F-Freeman: Oh. Nice catch, Knock Out.
Knock Out: Thanks. Anyways, I found another key to another world.
Optimus Prime: What is it?
Nighlock:(flies up and sees it is a literal key, but is faintly glowing green) Why is it glowing?
Knock Out: It must be one of those "it glows brighter the closer you get to the door" kind of keys.
Nighlock: How bright was it glowing when you found it?
Knock Out: Like a dimming light, but clearly trying to come on.
Major Malfunction: That means the door was halfway from your position.
Ranyx: Let me pinpoint this thing.
[He then grabs the key and turns in all directions]
Flitter: I hope you can do it.
[he then sees it glow a little brighter when facing West]
Nighlock: You are warmer, Ryan.
Ranyx: I'm Ranyx. I'm Ryan's Nobody, Nighlock.
[He moves foward]
Nighlock:[opens a portal to where Knock Out found the key]
[they go inside as they continue moving, the key glows brighter and brighter]
Ranyx: Nearly there.
[He hums the tune "Shiny" as he move closer and the key glows more brighter]
Ranyx: Too bright!