@Nectar:
Seriously, bring back old rangers for cameos. You go over two decades worth.
I dunno. Maybe it'd be different for anyone young enough to have grown up on any of the middle series, but the original cast were the only ones that stuck around for multiple years and have any real nostalgia value going for them. Selwyn Ward is the last one I can think of that crossed over through multiple shows and played multiple rangers that weren't back to back. Turbo, Galaxy, Wild Force?
They also had Ricardo Medina who was in WIld Force and Samurai (10 years apart!) but… he played different characters rather than a returning one. So...
Tommy is the only one anyone really cares about and I think they've dragged him out about as many times as they can... and even his part in the franchise started TWENTY FIVE YEARS AGO.
As for getting Billy back, well... he's pretty much retired from acting, and he's in his fifties now so that would be weirdish, but he also left the show for... reasons.
They drag out whoever they can every couple years for the anniversaries at least?