No, the Champion’s Cup rematches have no relation to Online whatsoever.
By ‘invite any of 10 trainers’, it means that you can choose any of the following characters to take part in the tournament:
Milo
Nessa
Kabu
Bea(SW only)/Allister(SH only)
Bede
Gordie(SW only)/Melony(SH only)
Piers
Raihan
Marnie
Leon
Inviting one of the above listed characters does not guarantee that you will battle them, as the first matches are selected randomly and the character you invited may lose to someone else.
In addition to these, Gym Challengers may take part. You cannot invite these personally; they play more of a filler role. These are:
Yue (normal type specialist)
Polaire (bug type specialist)
Kent (flying type specialist)
Vega (water type specialist)
Cher (rock type specialist)
Deneb (fighting type specialist)
Icla (poison type specialist)
Wei (ghost type specialist)
Izar (ice type specialist)
Dunne (ground type specialist)
Pia (grass type specialist)
Corvin (electric type specialist)
Terry (dragon type specialist)
Theemin (steel type specialist)
Phoebus (fire type specialist)
None of these trainers use Dynamax.
Source and experience
