England midfielder Delph has been linked with an £8m summer switch to the Etihad Stadium and Richards, who left City to join Villa on a free transfer this summer, is ideally placed to offer advice.
Defender Richards does not think it is a decision the 25-year-old should take lightly and would not recommend moving, even to a title-challenging side, without being confident of regular action.
Richards himself struggled to hold down a place in his final years at City due to a series of injuries and the form of Pablo Zabaleta, and spent last season on loan at Fiorentina.
Richards said: “It’s tough isn’t it? If he’s got guarantees to play… He’s been unbelievable for Aston Villa. Every player wants to play at the highest level. If he’s going to be playing Champions League… I don’t know, but if he’s going there to be a squad player, then no.
“James Milner has played six or seven positions and still wanted to leave. So if he gets assurances he’s going to play then the decision is his. I wouldn’t say don’t go to Manchester City, because if he’s playing well he could play. If you’re good enough you’ll play.
“It’s just being given that chance. If he (City manager Manuel Pellegrini) is going to give him the chance to play then it’s hard to turn down the chance of playing Champions League football.
“To be fair he has asked me what I think about the situation. I told him I can’t comment to be honest. I don’t want to say go there and then he (Pellegrini) doesn’t play him – he’ll be ringing me up afterwards!”
Richards, 27, played a key role in City’s FA Cup and Premier League triumphs of 2011 and 2012 respectively but was then restricted to just nine league appearances over the next two seasons.
He won the last of his 13 England caps in February 2012 and, after also struggling for game time in Italy, hopes the move to Villa can revive his career.
He adds that the international factor is also something Delph must consider if weighing up a move to join City’s star-studded squad.
Richards said: “It makes it difficult because next year is the Euros. If you go to Man City and find yourself only playing 10 games and someone (else) has a really good season that player is going to play for England. Things can change.
“Sometimes you’ve got to strike when the iron’s hot and Delph is playing well but it’s a difficult decision. I’m sure he’ll make the right one.”
Richards is Villa’s first signing of the summer but manager Tim Sherwood is keen to add new faces to bolster a squad that narrowly avoided relegation last season.
Losing Delph would be an undoubted blow to plans as would the departure of striker Christian Benteke, who has been strongly linked with Liverpool.
Richards said: “You need good players. You can’t be average players and expect to finish first in the league. You need winners in your team. With Delphy we have that. Whether he stays or not I don’t know.
“Benteke? I don’t know. If he leaves it will be – not a problem – but he’s one of the best strikers in the league. So it’s going to be difficult if he leaves. But I think we’ve got a good group of lads. I’ve been impressed with the first two training sessions.
“I’ve obviously trained with the best at Man City and that’s been really high, but the lads here are confident and hopefully we can take that into the new season.”